rs386833531

Positions:

• chr9-6587205-G-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000170.3(GLDC):​c.1786C>T​(p.Arg596*) variant causes a stop gained change. The variant allele was found at a frequency of 0.0000041 in 1,461,682 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: GLDC NM_000170.3 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 3.64

Genes affected

GLDC (HGNC:4313): (glycine decarboxylase) Degradation of glycine is brought about by the glycine cleavage system, which is composed of four mitochondrial protein components: P protein (a pyridoxal phosphate-dependent glycine decarboxylase), H protein (a lipoic acid-containing protein), T protein (a tetrahydrofolate-requiring enzyme), and L protein (a lipoamide dehydrogenase). The protein encoded by this gene is the P protein, which binds to glycine and enables the methylamine group from glycine to be transferred to the T protein. Defects in this gene are a cause of nonketotic hyperglycinemia (NKH).[provided by RefSeq, Jan 2010]

GLDC (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 9-6587205-G-A is Pathogenic according to our data. Variant chr9-6587205-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 56050.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr9-6587205-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GLDC	NM_000170.3	c.1786C>T	p.Arg596*	stop_gained	15/25	ENST00000321612.8	NP_000161.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GLDC	ENST00000321612.8	c.1786C>T	p.Arg596*	stop_gained	15/25	1	NM_000170.3	ENSP00000370737.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251482 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135916

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000410 AC: 6 AN: 1461682 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727162

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000232

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000360

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Alfa AF: 0.555 Hom.: 8748

Bravo AF: 0.0000151

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Glycine encephalopathy Pathogenic:5

Likely pathogenic, no assertion criteria provided	literature only	Juha Muilu Group; Institute for Molecular Medicine Finland (FIMM)	-	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Jan 24, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Oct 31, 2018	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 20, 2024	This sequence change creates a premature translational stop signal (p.Arg596*) in the GLDC gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in GLDC are known to be pathogenic (PMID: 16601880). This variant is present in population databases (rs386833531, gnomAD 0.003%). This premature translational stop signal has been observed in individuals with non-ketotic hyperglycinemia (PMID: 16450403, 28302194). ClinVar contains an entry for this variant (Variation ID: 56050). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 15, 2022	Variant summary: GLDC c.1786C>T (p.Arg596X) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory and is associated with Non-Ketotic Hyperglycinemia in HGMD. The variant allele was found at a frequency of 1.2e-05 in 251482 control chromosomes (gnomAD). c.1786C>T has been reported in the literature in compound heterozygote and homozygote individuals affected with glycine encephalopathy (Non-Ketotic Hyperglycinemia) (examples: Gao_2017, Kure_2006), bi-allelic neonatal case of multiple congenital anomalies (Wang_2020) and a heterozygous patient with developmental-epileptic encephalopathy (Mitta_2020). These data indicate that the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as pathogenic (n=2)/likely pathogenic (n=1). Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.62
CADD	Pathogenic	49
DANN	Uncertain	1.0
Eigen	Pathogenic	0.95
Eigen_PC	Pathogenic	0.81
FATHMM_MKL	Uncertain	0.92	D
Vest4		0.89
GERP RS		5.3
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs386833531; hg19: chr9-6587205; COSMIC: COSV100394039; COSMIC: COSV100394039;