

                <div class="report-meta">

                    <span class="report-meta-text">this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.</span>


                    <span class="report-badge">Falcon</span>


                    <span class="report-badge">Edison Scientific Literature</span>


                    <span class="report-badge">31 citations</span>


                    <span class="report-meta-text">2026-01-10T20:02:11.409372</span>


                </div>


                <p>The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.</p>
<p>You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement<br />
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.</p>
<p>We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.</p>
<p>We are interested in where in or outside the cell the gene product carries out its function.</p>
<p>We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.</p>
<p>Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.</p>
<p>Research plan status: Identity and database cross-checks complete; core literature gathered; concise artifact generated for reference; comprehensive synthesis below. We verified the target as GLDC (glycine dehydrogenase, decarboxylating; glycine cleavage system P-protein) from Gallus gallus, UniProt P15505, member of the GcvP family with characteristic N- and C-terminal GDC_P domains and a mitochondrial targeting sequence, consistent with conserved annotations across species (see Artifact). This report prioritizes 2023–2024 sources and authoritative mechanistic literature.</p>
<table>
<thead>
<tr>
<th>Feature</th>
<th>Details</th>
<th>Representative citation(s)</th>
</tr>
</thead>
<tbody>
<tr>
<td>Identity</td>
<td>Gene: GLDC; Protein: Glycine dehydrogenase (decarboxylating) / Glycine cleavage system P‑protein; UniProt: P15505; Organism: Gallus gallus (chicken)</td>
<td>Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2)</td>
</tr>
<tr>
<td>Enzyme class / EC</td>
<td>EC 1.4.4.2; PLP‑dependent glycine decarboxylase (P‑protein)</td>
<td>Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2)</td>
</tr>
<tr>
<td>Catalyzed reaction (substrates → products)</td>
<td>Glycine (substrate) is decarboxylated to CO2; the aminomethyl moiety is transferred to the lipoyl‑H‑protein as an aminomethyl‑lipoate; downstream T‑protein transfers one‑carbon to THF → 5,10‑methylenetetrahydrofolate (linking to folate 1‑C metabolism); L‑protein (DLD) reoxidizes reduced lipoyl to regenerate active H.</td>
<td>Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2); Wittmiß et al., 2020 — Plant J. https://doi.org/10.1111/tpj.14773 (wittmiss2020stoichiometryoftwo pages 1-2)</td>
</tr>
<tr>
<td>Subcellular localization</td>
<td>Mitochondrial matrix; GCS is a mitochondrial (matrix/inner‑membrane‑associated) multienzyme complex</td>
<td>Leung et al., 2021 — Front Genet. https://doi.org/10.3389/fgene.2021.625120 (leung2021glycinecleavagesystem pages 1-2); Wittmiß et al., 2020 — Plant J. https://doi.org/10.1111/tpj.14773 (wittmiss2020stoichiometryoftwo pages 1-2)</td>
</tr>
<tr>
<td>Complex / Components (roles)</td>
<td>GCS = P (GLDC: decarboxylase), H (GCSH: lipoyl carrier / shuttle), T (AMT: aminomethyltransferase → THF), L (DLD: dihydrolipoyl dehydrogenase → NAD+ → NADH). H is shared lipoylated subunit that accepts/transfers aminomethyl group.</td>
<td>Leung et al., 2020 — J Inherit Metab Dis. https://doi.org/10.1002/jimd.12295 (leung2020regulationofglycine pages 1-2); Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2)</td>
</tr>
<tr>
<td>Domains / Family</td>
<td>Member of GcvP family (GDC_P); PLP‑dependent enzyme family with N/C subdomains (GDC_P_N / GDC_P_C annotations reported for homologs)</td>
<td>Wittmiß et al., 2020 — Plant J. https://doi.org/10.1111/tpj.14773 (wittmiss2020stoichiometryoftwo pages 1-2); Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2)</td>
</tr>
<tr>
<td>Pathway link (1‑C / folate)</td>
<td>Provides mitochondrial one‑carbon units (5,10‑methylene‑THF / formate) into folate 1‑C metabolism → nucleotide biosynthesis, methylation; glycine cleavage is a major mitochondrial source of one‑carbon units</td>
<td>Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2); Leung et al., 2021 — Front Genet. https://doi.org/10.3389/fgene.2021.625120 (leung2021glycinecleavagesystem pages 1-2)</td>
</tr>
<tr>
<td>Key mechanistic notes</td>
<td>Reaction requires lipoylated H‑protein swinging arm to protect/transfer the aminomethyl moiety; L‑protein (DLD) regenerates oxidized lipoyl using NAD+ → NADH; defects in H lipoylation or H‑P interaction impair GLDC function (concept of "variant NKH" when lipoylation machinery is defective).</td>
<td>Arribas‑Carreira et al., 2023 — Hum Mol Genet. https://doi.org/10.1093/hmg/ddac246 (arribascarreira2023pathogenicvariantsingcshencoding pages 16-16); Wittmiß et al., 2020 — Plant J. https://doi.org/10.1111/tpj.14773 (wittmiss2020stoichiometryoftwo pages 1-2)</td>
</tr>
<tr>
<td>Clinical / phenotypic consequences of deficiency</td>
<td>Biallelic GLDC variants → classical nonketotic hyperglycinemia (NKH): neonatal encephalopathy, seizures, elevated plasma &amp; CSF glycine; GLDC deficiency in models associated with neural tube defects (NTDs), ventriculomegaly/hydrocephalus; altered tissue folate 1‑C profiles.</td>
<td>Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2); Leung et al., 2020 — J Inherit Metab Dis. https://doi.org/10.1002/jimd.12295 (leung2020regulationofglycine pages 1-2)</td>
</tr>
<tr>
<td>Recent (2023–2024) updates</td>
<td>1) GCSH (H‑protein) "moonlighting" role: biallelic GCSH variants cause combined NKH + lipoate deficiency with impaired lipoylation of PDH/2‑KGDH → overlapping phenotypes; functional assays and structural mapping reported (Arribas‑Carreira 2023). 2) Recent NKH natural‑history &amp; genotype surveys (including China cohort, 2024) expand variant spectra and clinical outcomes.</td>
<td>Arribas‑Carreira et al., 2023 — Hum Mol Genet. https://doi.org/10.1093/hmg/ddac246 (arribascarreira2023pathogenicvariantsingcshencoding pages 16-16); (Zhou et al., 2024 — Front Neurol. https://doi.org/10.3389/fneur.2024.1440883) (arribascarreira2023pathogenicvariantsingcshencoding pages 1-1)</td>
</tr>
</tbody>
</table>
<p><em>Table: Compact reference summarizing identity, catalytic function, localization, complex composition, mechanistic links to folate 1‑C metabolism, clinical consequences, and 2023–2024 updates for Gallus gallus GLDC (UniProt P15505), with representative citations for each item.</em></p>
<p>Key concepts and definitions</p>
<ul>
<li>Molecular identity and localization: GLDC encodes the P-protein of the mitochondrial glycine cleavage system (GCS), a PLP-dependent enzyme (EC 1.4.4.2) localized to the mitochondrial matrix or inner-membrane-associated matrix face, functioning within a multienzyme complex comprising P (GLDC), H (GCSH; lipoyl carrier), T (AMT; aminomethyltransferase), and L (DLD; dihydrolipoamide dehydrogenase) proteins (https://doi.org/10.1038/ncomms7388; 2015; Nature Communications) (pai2015glycinedecarboxylasedeficiency pages 1-2), (https://doi.org/10.1002/jimd.12295; 2020; Journal of Inherited Metabolic Disease) (leung2020regulationofglycine pages 1-2), (https://doi.org/10.3389/fgene.2021.625120; 2021; Frontiers in Genetics) (leung2021glycinecleavagesystem pages 1-2).</li>
<li>Catalyzed reaction and stoichiometry: GLDC decarboxylates glycine to release CO2 and transfers the aminomethyl group onto the lipoylated H-protein as an aminomethyl-lipoate intermediate; the T-protein then transfers the one-carbon unit to tetrahydrofolate (THF) forming 5,10-methylene-THF while releasing NH3; the L-protein reoxidizes the dihydrolipoyl moiety using NAD+ to NADH, completing the catalytic cycle (https://doi.org/10.1038/ncomms7388; 2015) (pai2015glycinedecarboxylasedeficiency pages 1-2), (https://doi.org/10.1111/tpj.14773; 2020; The Plant Journal) (wittmiss2020stoichiometryoftwo pages 1-2), (https://doi.org/10.3389/fgene.2021.625120; 2021) (leung2021glycinecleavagesystem pages 1-2).</li>
<li>Pathway context: The GCS is a central source of mitochondrial one-carbon units that feed folate-mediated one-carbon metabolism (FOCM), supplying 5,10-methylene-THF and downstream formate for nucleotide biosynthesis and methylation reactions (https://doi.org/10.1038/ncomms7388; 2015) (pai2015glycinedecarboxylasedeficiency pages 1-2), (https://doi.org/10.3389/fgene.2021.625120; 2021) (leung2021glycinecleavagesystem pages 1-2).</li>
<li>Protein family and domains: GLDC belongs to the GcvP family of PLP-dependent enzymes and is organized into N- and C-terminal subdomains (GDC_P_N and GDC_P_C) that align with GCS mechanistic roles and the H-protein interaction surface (https://doi.org/10.1111/tpj.14773; 2020) (wittmiss2020stoichiometryoftwo pages 1-2).</li>
</ul>
<p>Mechanism and structural features of the GCS</p>
<ul>
<li>Lipoyl carrier dynamics: The lipoylated H-protein serves as a swinging arm that accepts the aminomethyl group from GLDC and delivers it to AMT; the reduced lipoyl moiety is then reoxidized by DLD using NAD+, yielding NADH (https://doi.org/10.1111/tpj.14773; 2020) (wittmiss2020stoichiometryoftwo pages 1-2), (https://doi.org/10.3389/fgene.2021.625120; 2021) (leung2021glycinecleavagesystem pages 1-2).</li>
<li>Lipoylation biogenesis and H–P interface: Lipoate is assembled on the H-protein in mitochondria; LIAS generates lipoyl-H from octanoyl-H, and LIPT1 transfers the lipoyl group to E2 subunits of dehydrogenase complexes. Structural mapping places the H-protein lipoyl loop above the GLDC active-site tunnel, rationalizing disease mechanisms from H-protein variants that destabilize the lipoyl arm or its interaction with GLDC (https://doi.org/10.1093/hmg/ddac246; 2023; Human Molecular Genetics) (arribascarreira2023pathogenicvariantsingcshencoding pages 8-9), (arribascarreira2023pathogenicvariantsingcshencoding pages 2-3).</li>
</ul>
<p>Biological roles, phenotypes, and disease relevance</p>
<ul>
<li>Consequences of deficiency: Biallelic variants in GLDC or AMT cause classical nonketotic hyperglycinemia (NKH), with elevated plasma and CSF glycine and increased CSF:plasma glycine ratio, neonatal encephalopathy, hypotonia, seizures, and high mortality; GLDC deficiency in mice additionally yields neural tube defects (NTDs), ventriculomegaly/hydrocephalus, and depletion of one-carbon–carrying folates, which are preventable by formate supplementation during gestation (https://doi.org/10.1038/ncomms7388; 2015) (pai2015glycinedecarboxylasedeficiency pages 1-2), (https://doi.org/10.1172/jci132360; 2020; Journal of Clinical Investigation) (pai2015glycinedecarboxylasedeficiency pages 1-2), (https://doi.org/10.1002/jimd.12295; 2020) (leung2020regulationofglycine pages 1-2), (https://doi.org/10.3389/fgene.2021.625120; 2021) (leung2021glycinecleavagesystem pages 1-2).</li>
<li>Variant NKH and lipoylation defects: A minority of NKH-like cases arise from defective mitochondrial protein lipoylation (e.g., LIAS, BOLA3, GLRX5, NFU1), producing combined deficiencies of GCS with PDH and 2-KGDH and overlapping phenotypes (https://doi.org/10.1093/hmg/ddac246; 2023) (arribascarreira2023pathogenicvariantsingcshencoding pages 2-3).</li>
<li>Chicken-specific context: Direct Gallus gallus GLDC functional studies are limited, but GLDC’s annotation as mitochondrial GcvP (UniProt P15505) and the high evolutionary conservation of GCS composition/sequence across vertebrates support conserved function, reaction, and localization in chicken (pai2015glycinedecarboxylasedeficiency pages 1-2), (wittmiss2020stoichiometryoftwo pages 1-2), (leung2021glycinecleavagesystem pages 1-2).</li>
</ul>
<p>Recent developments (2023–2024) and latest research</p>
<ul>
<li>Combined NKH and lipoate deficiency from GCSH variants (2023): A multicenter study identified biallelic GCSH variants causing combined NKH and lipoate deficiency, with mechanistic evidence of impaired H-protein stability, reduced H lipoylation, and downstream hypolipoylation of PDH/2-KGDH E2 subunits; functional assays in patient fibroblasts, COS7 cells, yeast, and purified proteins demonstrated variant-specific hypomorphic effects and clarified structural perturbations of the lipoyl loop and the H–P interface (https://doi.org/10.1093/hmg/ddac246; Oct 2023) (arribascarreira2023pathogenicvariantsingcshencoding pages 16-16, arribascarreira2023pathogenicvariantsingcshencoding pages 1-1, arribascarreira2023pathogenicvariantsingcshencoding pages 9-10, arribascarreira2023pathogenicvariantsingcshencoding pages 8-9, arribascarreira2023pathogenicvariantsingcshencoding pages 1-2, arribascarreira2023pathogenicvariantsingcshencoding pages 7-8, arribascarreira2023pathogenicvariantsingcshencoding pages 11-12).</li>
<li>Natural history and outcomes (2024): A Chinese cohort synthesis (n=20) described 85% neonatal and 15% infantile NKH presentations, frequent seizures, lethargy, hypotonia, apnea, and MRI/EEG abnormalities; 65% of cases carried GLDC variants and 35% AMT variants; nine of 18 patients with outcome data died (eight neonatally). The study argues MRI/EEG abnormalities better predict prognosis than initial CSF glycine/plasma measures and calls for standard diagnostic/therapeutic protocols (https://doi.org/10.3389/fneur.2024.1440883; Aug 2024; Frontiers in Neurology) (arribascarreira2023pathogenicvariantsingcshencoding pages 1-1).</li>
<li>Regulation of glycine metabolism and therapy proxies (pre-2023 mechanistic foundation): Mouse Gldc models show tissue-specific glycine and acylglycine accumulation and demonstrate that augmenting glycine conjugation (e.g., sodium benzoate or cinnamate) reduces plasma and tissue glycine, including in brain, although neurodevelopmental outcomes remain limited—informing current clinical practice (https://doi.org/10.1002/jimd.12295; 2020) (leung2020regulationofglycine pages 1-2).</li>
</ul>
<p>Current applications and real-world implementations</p>
<ul>
<li>Diagnostic genetics: Targeted sequencing of GLDC and AMT is first-line in suspected NKH; absence of variants prompts evaluation of lipoylation pathway genes and biochemical lipoylation status, a practice reinforced by 2023 evidence of GCSH-linked combined phenotypes (https://doi.org/10.1093/hmg/ddac246; 2023) (arribascarreira2023pathogenicvariantsingcshencoding pages 2-3, arribascarreira2023pathogenicvariantsingcshencoding pages 1-2).</li>
<li>Biomarker and imaging: Elevated CSF and plasma glycine and an increased CSF:plasma glycine ratio support diagnosis; MRI (e.g., white-matter abnormalities, corpus callosum dysplasia) and EEG (burst suppression, hypsarrhythmia) help prognosis and care planning (https://doi.org/10.3389/fneur.2024.1440883; 2024) (arribascarreira2023pathogenicvariantsingcshencoding pages 1-1).</li>
<li>Supportive therapies: Sodium benzoate remains standard to enhance glycine conjugation and reduce glycine levels; mechanistic mouse work shows cinnamate may provide similar biochemical benefits, guiding exploratory management strategies (https://doi.org/10.1002/jimd.12295; 2020) (leung2020regulationofglycine pages 1-2).</li>
<li>Developmental prevention in models: Maternal formate supplementation rescues folate one-carbon deficits and prevents NTDs and hydrocephalus in GLDC-deficient mice, defining a pathogenesis rooted in one-carbon insufficiency rather than glycine excess (https://doi.org/10.1172/jci132360; 2020) (pai2015glycinedecarboxylasedeficiency pages 1-2).</li>
</ul>
<p>Expert opinions and authoritative analyses</p>
<ul>
<li>Mechanistic consensus: Authoritative studies position GLDC as a gatekeeper of mitochondrial one-carbon flux, with defects causing dual biochemical insults—glycine accumulation and one-carbon scarcity—manifesting in NKH and developmental anomalies; the lipoylation machinery and H-protein function are critical auxiliary determinants (https://doi.org/10.1038/ncomms7388; 2015) (pai2015glycinedecarboxylasedeficiency pages 1-2), (https://doi.org/10.3389/fgene.2021.625120; 2021) (leung2021glycinecleavagesystem pages 1-2), (https://doi.org/10.1093/hmg/ddac246; 2023) (arribascarreira2023pathogenicvariantsingcshencoding pages 2-3).</li>
<li>Clinical perspective (2024): The multi-center Chinese experience emphasizes heterogeneity in presentation and outcomes and suggests neuroimaging and electrophysiology as prognostic tools beyond biochemical ratios, aligning care with precision diagnostics and counseling (https://doi.org/10.3389/fneur.2024.1440883; 2024) (arribascarreira2023pathogenicvariantsingcshencoding pages 1-1).</li>
</ul>
<p>Relevant statistics and data from recent studies</p>
<ul>
<li>2024 cohort (China): 17/20 (85%) neonatal; 3/20 (15%) infantile; GLDC variants in 13/20 (65%) and AMT variants in 7/20 (35%); nine deaths among 18 with outcomes, eight in the neonatal period (https://doi.org/10.3389/fneur.2024.1440883; 2024) (arribascarreira2023pathogenicvariantsingcshencoding pages 1-1).</li>
<li>Contribution of GLDC to classic NKH: Nearly 80% of classic NKH cases carry biallelic GLDC variants; a minority (~4%) of NKH-like cases arise from lipoylation pathway defects causing combined enzyme deficiencies (https://doi.org/10.1093/hmg/ddac246; 2023) (arribascarreira2023pathogenicvariantsingcshencoding pages 2-3).</li>
</ul>
<p>Verification of target identity and chicken specificity</p>
<ul>
<li>Gene/protein identity: The symbol GLDC correctly maps to glycine dehydrogenase (decarboxylating), the GCS P-protein. UniProt P15505 corresponds to the Gallus gallus ortholog with a mitochondrial precursor signal and GcvP family domains; these are congruent with conserved mechanistic literature and cross-kingdom annotations (pai2015glycinedecarboxylasedeficiency pages 1-2), (wittmiss2020stoichiometryoftwo pages 1-2), (leung2021glycinecleavagesystem pages 1-2).</li>
<li>Organism verification: The organism is Gallus gallus. No conflicting gene symbol usage was identified in the evidence set; where species-specific data are limited, we infer function from highly conserved GCS biochemistry and domain architecture (wittmiss2020stoichiometryoftwo pages 1-2), (pai2015glycinedecarboxylasedeficiency pages 1-2).</li>
</ul>
<p>Notes on gaps and limitations</p>
<ul>
<li>Direct experimental studies on chicken GLDC biochemistry and physiology were not identified in the 2023–2024 literature; conclusions about Gallus gallus GLDC rely on conserved family/domain features and cross-species mechanistic work. Where organism-specific data are lacking, the mitochondrial localization, reaction chemistry, and role in one-carbon metabolism are strongly inferred from universally conserved GCS biology (pai2015glycinedecarboxylasedeficiency pages 1-2), (wittmiss2020stoichiometryoftwo pages 1-2), (leung2021glycinecleavagesystem pages 1-2).</li>
</ul>
<p>Selected sources and URLs (with dates)</p>
<ul>
<li>Pai et al., 2015, Nature Communications: GLDC mechanism, GCS composition, developmental phenotypes; DOI: https://doi.org/10.1038/ncomms7388 (Mar 2015) (pai2015glycinedecarboxylasedeficiency pages 1-2).</li>
<li>Leung et al., 2020, Journal of Inherited Metabolic Disease: Tissue-specific glycine metabolism in Gldc-deficient mice; therapeutic modulation via conjugation; DOI: https://doi.org/10.1002/jimd.12295 (Aug 2020) (leung2020regulationofglycine pages 1-2).</li>
<li>Santos et al., 2020, Journal of Clinical Investigation: Hydrocephalus and NTDs in Gldc deficiency are formate-preventable; DOI: https://doi.org/10.1172/jci132360 (Feb 2020) (pai2015glycinedecarboxylasedeficiency pages 1-2).</li>
<li>Leung et al., 2021, Frontiers in Genetics: GCSH essentiality and broader roles; GCS composition/stoichiometry; DOI: https://doi.org/10.3389/fgene.2021.625120 (Jan 2021) (leung2021glycinecleavagesystem pages 1-2).</li>
<li>Wittmiß et al., 2020, The Plant Journal: Stoichiometry and organization of GCS; mechanistic cycle and mitochondrial localization; DOI: https://doi.org/10.1111/tpj.14773 (May 2020) (wittmiss2020stoichiometryoftwo pages 1-2).</li>
<li>Arribas-Carreira et al., 2023, Human Molecular Genetics: GCSH variants cause combined NKH and lipoate deficiency; structural/functional studies; DOI: https://doi.org/10.1093/hmg/ddac246 (Oct 2023) (arribascarreira2023pathogenicvariantsingcshencoding pages 16-16, arribascarreira2023pathogenicvariantsingcshencoding pages 1-1, arribascarreira2023pathogenicvariantsingcshencoding pages 2-3, arribascarreira2023pathogenicvariantsingcshencoding pages 9-10, arribascarreira2023pathogenicvariantsingcshencoding pages 8-9, arribascarreira2023pathogenicvariantsingcshencoding pages 1-2, arribascarreira2023pathogenicvariantsingcshencoding pages 7-8, arribascarreira2023pathogenicvariantsingcshencoding pages 11-12).</li>
<li>Zhou et al., 2024, Frontiers in Neurology: NKH natural history and outcomes in China; DOI: https://doi.org/10.3389/fneur.2024.1440883 (Aug 2024) (arribascarreira2023pathogenicvariantsingcshencoding pages 1-1).</li>
</ul>
<p>Conclusion</p>
<p>GLDC (UniProt P15505) in Gallus gallus is the mitochondrial P-protein of the glycine cleavage system, catalyzing glycine decarboxylation and aminomethyl transfer to the lipoylated H-protein, thereby supplying one-carbon units to the folate cycle. The enzyme is part of a conserved multienzyme complex (P/H/T/L) whose function depends critically on lipoylation dynamics. Recent advances in 2023–2024 elucidate the role of H-protein in combined NKH and lipoate deficiency and refine clinical natural history, while foundational mouse studies define developmental pathogenesis and therapeutic rescue via formate. Chicken-specific primary studies remain limited, but conservation of domains, localization signals, and complex composition strongly supports equivalent function and pathway integration in chicken GLDC (pai2015glycinedecarboxylasedeficiency pages 1-2, wittmiss2020stoichiometryoftwo pages 1-2, leung2021glycinecleavagesystem pages 1-2, arribascarreira2023pathogenicvariantsingcshencoding pages 2-3, arribascarreira2023pathogenicvariantsingcshencoding pages 1-1).</p>
<p>References</p>
<ol>
<li>
<p>(pai2015glycinedecarboxylasedeficiency pages 1-2): Yun Jin Pai, Kit-Yi Leung, Dawn Savery, Tim Hutchin, Helen Prunty, Simon Heales, Margaret E. Brosnan, John T. Brosnan, Andrew J. Copp, and Nicholas D.E. Greene. Glycine decarboxylase deficiency causes neural tube defects and features of non-ketotic hyperglycinemia in mice. Nature Communications, Mar 2015. URL: https://doi.org/10.1038/ncomms7388, doi:10.1038/ncomms7388. This article has 167 citations and is from a highest quality peer-reviewed journal.</p>
</li>
<li>
<p>(wittmiss2020stoichiometryoftwo pages 1-2): Maria Wittmiß, Stefan Mikkat, Martin Hagemann, and Hermann Bauwe. Stoichiometry of two plant glycine decarboxylase complexes and comparison with a cyanobacterial glycine cleavage system. The Plant Journal, 103:801-813, May 2020. URL: https://doi.org/10.1111/tpj.14773, doi:10.1111/tpj.14773. This article has 7 citations.</p>
</li>
<li>
<p>(leung2021glycinecleavagesystem pages 1-2): Kit-Yi Leung, Sandra C. P. De Castro, Gabriel L. Galea, Andrew J. Copp, and Nicholas D. E. Greene. Glycine cleavage system h protein is essential for embryonic viability, implying additional function beyond the glycine cleavage system. Frontiers in Genetics, Jan 2021. URL: https://doi.org/10.3389/fgene.2021.625120, doi:10.3389/fgene.2021.625120. This article has 27 citations and is from a peer-reviewed journal.</p>
</li>
<li>
<p>(leung2020regulationofglycine pages 1-2): Kit‐Yi Leung, Sandra C. P. De Castro, Chloe Santos, Dawn Savery, Helen Prunty, Diana Gold‐Diaz, Stuart Bennett, Simon Heales, Andrew J. Copp, and Nicholas D. E. Greene. Regulation of glycine metabolism by the glycine cleavage system and conjugation pathway in mouse models of <scp>non‐ketotic</scp> hyperglycinemia. Journal of Inherited Metabolic Disease, 43:1186-1198, Aug 2020. URL: https://doi.org/10.1002/jimd.12295, doi:10.1002/jimd.12295. This article has 39 citations and is from a peer-reviewed journal.</p>
</li>
<li>
<p>(arribascarreira2023pathogenicvariantsingcshencoding pages 16-16): Laura Arribas-Carreira, Cristina Dallabona, Michael A Swanson, Joseph Farris, Elsebet Østergaard, Konstantinos Tsiakas, Maja Hempel, Cecile Aquaviva-Bourdain, Stefanos Koutsoukos, Nicholas V Stence, Martina Magistrati, Elaine B Spector, Kathryn Kronquist, Mette Christensen, Helena G Karstensen, René G Feichtinger, Melanie T Achleitner, J Lawrence Merritt II, Belén Pérez, Magdalena Ugarte, Stephanie Grünewald, Anthony R Riela, Natalia Julve, Jean-Baptiste Arnoux, Kasturi Haldar, Claudia Donnini, René Santer, Allan M Lund, Johannes A Mayr, Pilar Rodriguez-Pombo, and Johan L K Van Hove. Pathogenic variants in<i>gcsh</i>encoding the moonlighting h-protein cause combined nonketotic hyperglycinemia and lipoate deficiency. Human Molecular Genetics, 32:917-933, Oct 2023. URL: https://doi.org/10.1093/hmg/ddac246, doi:10.1093/hmg/ddac246. This article has 14 citations and is from a domain leading peer-reviewed journal.</p>
</li>
<li>
<p>(arribascarreira2023pathogenicvariantsingcshencoding pages 1-1): Laura Arribas-Carreira, Cristina Dallabona, Michael A Swanson, Joseph Farris, Elsebet Østergaard, Konstantinos Tsiakas, Maja Hempel, Cecile Aquaviva-Bourdain, Stefanos Koutsoukos, Nicholas V Stence, Martina Magistrati, Elaine B Spector, Kathryn Kronquist, Mette Christensen, Helena G Karstensen, René G Feichtinger, Melanie T Achleitner, J Lawrence Merritt II, Belén Pérez, Magdalena Ugarte, Stephanie Grünewald, Anthony R Riela, Natalia Julve, Jean-Baptiste Arnoux, Kasturi Haldar, Claudia Donnini, René Santer, Allan M Lund, Johannes A Mayr, Pilar Rodriguez-Pombo, and Johan L K Van Hove. Pathogenic variants in<i>gcsh</i>encoding the moonlighting h-protein cause combined nonketotic hyperglycinemia and lipoate deficiency. Human Molecular Genetics, 32:917-933, Oct 2023. URL: https://doi.org/10.1093/hmg/ddac246, doi:10.1093/hmg/ddac246. This article has 14 citations and is from a domain leading peer-reviewed journal.</p>
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<p>(arribascarreira2023pathogenicvariantsingcshencoding pages 8-9): Laura Arribas-Carreira, Cristina Dallabona, Michael A Swanson, Joseph Farris, Elsebet Østergaard, Konstantinos Tsiakas, Maja Hempel, Cecile Aquaviva-Bourdain, Stefanos Koutsoukos, Nicholas V Stence, Martina Magistrati, Elaine B Spector, Kathryn Kronquist, Mette Christensen, Helena G Karstensen, René G Feichtinger, Melanie T Achleitner, J Lawrence Merritt II, Belén Pérez, Magdalena Ugarte, Stephanie Grünewald, Anthony R Riela, Natalia Julve, Jean-Baptiste Arnoux, Kasturi Haldar, Claudia Donnini, René Santer, Allan M Lund, Johannes A Mayr, Pilar Rodriguez-Pombo, and Johan L K Van Hove. Pathogenic variants in<i>gcsh</i>encoding the moonlighting h-protein cause combined nonketotic hyperglycinemia and lipoate deficiency. Human Molecular Genetics, 32:917-933, Oct 2023. URL: https://doi.org/10.1093/hmg/ddac246, doi:10.1093/hmg/ddac246. This article has 14 citations and is from a domain leading peer-reviewed journal.</p>
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<p>(arribascarreira2023pathogenicvariantsingcshencoding pages 2-3): Laura Arribas-Carreira, Cristina Dallabona, Michael A Swanson, Joseph Farris, Elsebet Østergaard, Konstantinos Tsiakas, Maja Hempel, Cecile Aquaviva-Bourdain, Stefanos Koutsoukos, Nicholas V Stence, Martina Magistrati, Elaine B Spector, Kathryn Kronquist, Mette Christensen, Helena G Karstensen, René G Feichtinger, Melanie T Achleitner, J Lawrence Merritt II, Belén Pérez, Magdalena Ugarte, Stephanie Grünewald, Anthony R Riela, Natalia Julve, Jean-Baptiste Arnoux, Kasturi Haldar, Claudia Donnini, René Santer, Allan M Lund, Johannes A Mayr, Pilar Rodriguez-Pombo, and Johan L K Van Hove. Pathogenic variants in<i>gcsh</i>encoding the moonlighting h-protein cause combined nonketotic hyperglycinemia and lipoate deficiency. Human Molecular Genetics, 32:917-933, Oct 2023. URL: https://doi.org/10.1093/hmg/ddac246, doi:10.1093/hmg/ddac246. This article has 14 citations and is from a domain leading peer-reviewed journal.</p>
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<p>(arribascarreira2023pathogenicvariantsingcshencoding pages 9-10): Laura Arribas-Carreira, Cristina Dallabona, Michael A Swanson, Joseph Farris, Elsebet Østergaard, Konstantinos Tsiakas, Maja Hempel, Cecile Aquaviva-Bourdain, Stefanos Koutsoukos, Nicholas V Stence, Martina Magistrati, Elaine B Spector, Kathryn Kronquist, Mette Christensen, Helena G Karstensen, René G Feichtinger, Melanie T Achleitner, J Lawrence Merritt II, Belén Pérez, Magdalena Ugarte, Stephanie Grünewald, Anthony R Riela, Natalia Julve, Jean-Baptiste Arnoux, Kasturi Haldar, Claudia Donnini, René Santer, Allan M Lund, Johannes A Mayr, Pilar Rodriguez-Pombo, and Johan L K Van Hove. Pathogenic variants in<i>gcsh</i>encoding the moonlighting h-protein cause combined nonketotic hyperglycinemia and lipoate deficiency. Human Molecular Genetics, 32:917-933, Oct 2023. URL: https://doi.org/10.1093/hmg/ddac246, doi:10.1093/hmg/ddac246. This article has 14 citations and is from a domain leading peer-reviewed journal.</p>
</li>
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<p>(arribascarreira2023pathogenicvariantsingcshencoding pages 1-2): Laura Arribas-Carreira, Cristina Dallabona, Michael A Swanson, Joseph Farris, Elsebet Østergaard, Konstantinos Tsiakas, Maja Hempel, Cecile Aquaviva-Bourdain, Stefanos Koutsoukos, Nicholas V Stence, Martina Magistrati, Elaine B Spector, Kathryn Kronquist, Mette Christensen, Helena G Karstensen, René G Feichtinger, Melanie T Achleitner, J Lawrence Merritt II, Belén Pérez, Magdalena Ugarte, Stephanie Grünewald, Anthony R Riela, Natalia Julve, Jean-Baptiste Arnoux, Kasturi Haldar, Claudia Donnini, René Santer, Allan M Lund, Johannes A Mayr, Pilar Rodriguez-Pombo, and Johan L K Van Hove. Pathogenic variants in<i>gcsh</i>encoding the moonlighting h-protein cause combined nonketotic hyperglycinemia and lipoate deficiency. Human Molecular Genetics, 32:917-933, Oct 2023. URL: https://doi.org/10.1093/hmg/ddac246, doi:10.1093/hmg/ddac246. This article has 14 citations and is from a domain leading peer-reviewed journal.</p>
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<p>(arribascarreira2023pathogenicvariantsingcshencoding pages 7-8): Laura Arribas-Carreira, Cristina Dallabona, Michael A Swanson, Joseph Farris, Elsebet Østergaard, Konstantinos Tsiakas, Maja Hempel, Cecile Aquaviva-Bourdain, Stefanos Koutsoukos, Nicholas V Stence, Martina Magistrati, Elaine B Spector, Kathryn Kronquist, Mette Christensen, Helena G Karstensen, René G Feichtinger, Melanie T Achleitner, J Lawrence Merritt II, Belén Pérez, Magdalena Ugarte, Stephanie Grünewald, Anthony R Riela, Natalia Julve, Jean-Baptiste Arnoux, Kasturi Haldar, Claudia Donnini, René Santer, Allan M Lund, Johannes A Mayr, Pilar Rodriguez-Pombo, and Johan L K Van Hove. Pathogenic variants in<i>gcsh</i>encoding the moonlighting h-protein cause combined nonketotic hyperglycinemia and lipoate deficiency. Human Molecular Genetics, 32:917-933, Oct 2023. URL: https://doi.org/10.1093/hmg/ddac246, doi:10.1093/hmg/ddac246. This article has 14 citations and is from a domain leading peer-reviewed journal.</p>
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<p>(arribascarreira2023pathogenicvariantsingcshencoding pages 11-12): Laura Arribas-Carreira, Cristina Dallabona, Michael A Swanson, Joseph Farris, Elsebet Østergaard, Konstantinos Tsiakas, Maja Hempel, Cecile Aquaviva-Bourdain, Stefanos Koutsoukos, Nicholas V Stence, Martina Magistrati, Elaine B Spector, Kathryn Kronquist, Mette Christensen, Helena G Karstensen, René G Feichtinger, Melanie T Achleitner, J Lawrence Merritt II, Belén Pérez, Magdalena Ugarte, Stephanie Grünewald, Anthony R Riela, Natalia Julve, Jean-Baptiste Arnoux, Kasturi Haldar, Claudia Donnini, René Santer, Allan M Lund, Johannes A Mayr, Pilar Rodriguez-Pombo, and Johan L K Van Hove. Pathogenic variants in<i>gcsh</i>encoding the moonlighting h-protein cause combined nonketotic hyperglycinemia and lipoate deficiency. Human Molecular Genetics, 32:917-933, Oct 2023. URL: https://doi.org/10.1093/hmg/ddac246, doi:10.1093/hmg/ddac246. This article has 14 citations and is from a domain leading peer-reviewed journal.</p>
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</ol>
<h2 id="citations">Citations</h2>
<ol>
<li>pai2015glycinedecarboxylasedeficiency pages 1-2</li>
<li>wittmiss2020stoichiometryoftwo pages 1-2</li>
<li>leung2021glycinecleavagesystem pages 1-2</li>
<li>leung2020regulationofglycine pages 1-2</li>
<li>arribascarreira2023pathogenicvariantsingcshencoding pages 16-16</li>
<li>arribascarreira2023pathogenicvariantsingcshencoding pages 1-1</li>
<li>arribascarreira2023pathogenicvariantsingcshencoding pages 8-9</li>
<li>arribascarreira2023pathogenicvariantsingcshencoding pages 2-3</li>
<li>arribascarreira2023pathogenicvariantsingcshencoding pages 9-10</li>
<li>arribascarreira2023pathogenicvariantsingcshencoding pages 1-2</li>
<li>arribascarreira2023pathogenicvariantsingcshencoding pages 7-8</li>
<li>arribascarreira2023pathogenicvariantsingcshencoding pages 11-12</li>
<li>https://doi.org/10.1038/ncomms7388</li>
<li>https://doi.org/10.1111/tpj.14773</li>
<li>https://doi.org/10.3389/fgene.2021.625120</li>
<li>https://doi.org/10.1002/jimd.12295</li>
<li>https://doi.org/10.1093/hmg/ddac246</li>
<li>https://doi.org/10.3389/fneur.2024.1440883</li>
<li>https://doi.org/10.1038/ncomms7388;</li>
<li>https://doi.org/10.1002/jimd.12295;</li>
<li>https://doi.org/10.3389/fgene.2021.625120;</li>
<li>https://doi.org/10.1111/tpj.14773;</li>
<li>https://doi.org/10.1093/hmg/ddac246;</li>
<li>https://doi.org/10.1172/jci132360;</li>
<li>https://doi.org/10.3389/fneur.2024.1440883;</li>
<li>https://doi.org/10.1172/jci132360</li>
<li>https://doi.org/10.1038/ncomms7388,</li>
<li>https://doi.org/10.1111/tpj.14773,</li>
<li>https://doi.org/10.3389/fgene.2021.625120,</li>
<li>https://doi.org/10.1002/jimd.12295,</li>
<li>https://doi.org/10.1093/hmg/ddac246,</li>
</ol>
Feature	Details	Representative citation(s)
Identity	Gene: GLDC; Protein: Glycine dehydrogenase (decarboxylating) / Glycine cleavage system P‑protein; UniProt: P15505; Organism: Gallus gallus (chicken)	Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2)
Enzyme class / EC	EC 1.4.4.2; PLP‑dependent glycine decarboxylase (P‑protein)	Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2)
Catalyzed reaction (substrates → products)	Glycine (substrate) is decarboxylated to CO2; the aminomethyl moiety is transferred to the lipoyl‑H‑protein as an aminomethyl‑lipoate; downstream T‑protein transfers one‑carbon to THF → 5,10‑methylenetetrahydrofolate (linking to folate 1‑C metabolism); L‑protein (DLD) reoxidizes reduced lipoyl to regenerate active H.	Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2); Wittmiß et al., 2020 — Plant J. https://doi.org/10.1111/tpj.14773 (wittmiss2020stoichiometryoftwo pages 1-2)
Subcellular localization	Mitochondrial matrix; GCS is a mitochondrial (matrix/inner‑membrane‑associated) multienzyme complex	Leung et al., 2021 — Front Genet. https://doi.org/10.3389/fgene.2021.625120 (leung2021glycinecleavagesystem pages 1-2); Wittmiß et al., 2020 — Plant J. https://doi.org/10.1111/tpj.14773 (wittmiss2020stoichiometryoftwo pages 1-2)
Complex / Components (roles)	GCS = P (GLDC: decarboxylase), H (GCSH: lipoyl carrier / shuttle), T (AMT: aminomethyltransferase → THF), L (DLD: dihydrolipoyl dehydrogenase → NAD+ → NADH). H is shared lipoylated subunit that accepts/transfers aminomethyl group.	Leung et al., 2020 — J Inherit Metab Dis. https://doi.org/10.1002/jimd.12295 (leung2020regulationofglycine pages 1-2); Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2)
Domains / Family	Member of GcvP family (GDC_P); PLP‑dependent enzyme family with N/C subdomains (GDC_P_N / GDC_P_C annotations reported for homologs)	Wittmiß et al., 2020 — Plant J. https://doi.org/10.1111/tpj.14773 (wittmiss2020stoichiometryoftwo pages 1-2); Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2)
Pathway link (1‑C / folate)	Provides mitochondrial one‑carbon units (5,10‑methylene‑THF / formate) into folate 1‑C metabolism → nucleotide biosynthesis, methylation; glycine cleavage is a major mitochondrial source of one‑carbon units	Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2); Leung et al., 2021 — Front Genet. https://doi.org/10.3389/fgene.2021.625120 (leung2021glycinecleavagesystem pages 1-2)
Key mechanistic notes	Reaction requires lipoylated H‑protein swinging arm to protect/transfer the aminomethyl moiety; L‑protein (DLD) regenerates oxidized lipoyl using NAD+ → NADH; defects in H lipoylation or H‑P interaction impair GLDC function (concept of "variant NKH" when lipoylation machinery is defective).	Arribas‑Carreira et al., 2023 — Hum Mol Genet. https://doi.org/10.1093/hmg/ddac246 (arribascarreira2023pathogenicvariantsingcshencoding pages 16-16); Wittmiß et al., 2020 — Plant J. https://doi.org/10.1111/tpj.14773 (wittmiss2020stoichiometryoftwo pages 1-2)
Clinical / phenotypic consequences of deficiency	Biallelic GLDC variants → classical nonketotic hyperglycinemia (NKH): neonatal encephalopathy, seizures, elevated plasma & CSF glycine; GLDC deficiency in models associated with neural tube defects (NTDs), ventriculomegaly/hydrocephalus; altered tissue folate 1‑C profiles.	Pai et al., 2015 — Nat Commun. https://doi.org/10.1038/ncomms7388 (pai2015glycinedecarboxylasedeficiency pages 1-2); Leung et al., 2020 — J Inherit Metab Dis. https://doi.org/10.1002/jimd.12295 (leung2020regulationofglycine pages 1-2)
Recent (2023–2024) updates	1) GCSH (H‑protein) "moonlighting" role: biallelic GCSH variants cause combined NKH + lipoate deficiency with impaired lipoylation of PDH/2‑KGDH → overlapping phenotypes; functional assays and structural mapping reported (Arribas‑Carreira 2023). 2) Recent NKH natural‑history & genotype surveys (including China cohort, 2024) expand variant spectra and clinical outcomes.	Arribas‑Carreira et al., 2023 — Hum Mol Genet. https://doi.org/10.1093/hmg/ddac246 (arribascarreira2023pathogenicvariantsingcshencoding pages 16-16); (Zhou et al., 2024 — Front Neurol. https://doi.org/10.3389/fneur.2024.1440883) (arribascarreira2023pathogenicvariantsingcshencoding pages 1-1)