9-6550845-G-A

Position:

• chr9-6550845-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.2527C>T​(p.Arg843*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,112 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 Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: GLDC NM_000170.3 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 1.08

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 9-6550845-G-A is Pathogenic according to our data. Variant chr9-6550845-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 462875.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr9-6550845-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.2527C>T	p.Arg843*	stop_gained	21/25	ENST00000321612.8	NP_000161.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GLDC	ENST00000321612.8	c.2527C>T	p.Arg843*	stop_gained	21/25	1	NM_000170.3	ENSP00000370737.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461112 Hom.: 0 Cov.: 30 AF XY: 0.00000275 AC XY: 2 AN XY: 726908

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: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Glycine encephalopathy Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Oct 22, 2022	Variant summary: GLDC c.2527C>T (p.Arg843X) 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 within ClinVar (e.g. c.2614A>T [p.Lys872Ter]). The variant was absent in 251488 control chromosomes (gnomAD). c.2527C>T has been reported in the literature as a biallelic genotype in multiple individuals affected with Glycine Encephalopathy (Non-Ketotic Hyperglycinemia, Swanson_2015, Coughlin_2017). These data indicate that the variant is very likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Two ClinVar submitters have assessed the variant since 2014: one classified the variant as likely pathogenic and one as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 10, 2024	This sequence change creates a premature translational stop signal (p.Arg843*) 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 not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with glycine encephalopathy (PMID: 26179960). ClinVar contains an entry for this variant (Variation ID: 462875). For these reasons, this variant has been classified as Pathogenic. -
Likely pathogenic, no assertion criteria provided	clinical testing	Counsyl	Oct 27, 2017	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Dec 17, 2024

Nonsense variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 34426522, 31589614, 26179960) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	42
DANN	Uncertain	1.0
Eigen	Uncertain	0.41
Eigen_PC	Benign	0.21
FATHMM_MKL	Uncertain	0.80	D
Vest4		0.91
GERP RS		0.14

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: rs1554643360; hg19: chr9-6550845; COSMIC: COSV58684075;