NM_000170.3:c.1970G>A

Variant names:

• chr9-6558641-C-T
• rs1301895668
• NM_000170.3:c.1970G>A

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM2 PP3_Moderate PP5_Moderate

The NM_000170.3(GLDC):​c.1970G>A​(p.Ser657Asn) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,814 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S657I) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: GLDC NM_000170.3 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1 U:1
• Conservation: PhyloP100: 7.57
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• glycine encephalopathy

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Myriad Women’s Health, Labcorp Genetics (formerly Invitae), ClinGen
• glycine encephalopathy 1

  Inheritance: AR Classification: DEFINITIVE Submitted by: G2P
• infantile glycine encephalopathy

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• neonatal glycine encephalopathy

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• atypical glycine encephalopathy

  Inheritance: Unknown Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000296224 (HGNC:):

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.852
• PP5: Variant 9-6558641-C-T is Pathogenic according to our data. Variant chr9-6558641-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 550016.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GLDC	NM_000170.3	c.1970G>A	p.Ser657Asn	missense_variant	Exon 17 of 25	ENST00000321612.8	NP_000161.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GLDC	ENST00000321612.8	c.1970G>A	p.Ser657Asn	missense_variant	Exon 17 of 25	1	NM_000170.3	ENSP00000370737.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251452 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461814 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727216

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.0000224 AC: 1 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111932

Other (OTH) AF: 0.0000166 AC: 1 AN: 60396

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Glycine encephalopathy Pathogenic:1

Aug 09, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Ser657 amino acid residue in GLDC. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 26179960, 27362913). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt GLDC protein function. ClinVar contains an entry for this variant (Variation ID: 550016). This variant has been observed in individual(s) with nonketotic hyperglycinemia (PMID: 27362913). In at least one individual the data is consistent with the variant being in trans (on the opposite chromosome) from a pathogenic variant. This variant is not present in population databases (ExAC no frequency). This sequence change replaces serine with asparagine at codon 657 of the GLDC protein (p.Ser657Asn). The serine residue is highly conserved and there is a small physicochemical difference between serine and asparagine. -

Glycine encephalopathy 1 Uncertain:1

Dec 22, 2017

Counsyl

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Uncertain	0.15	D
BayesDel_noAF	Uncertain	0.060
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.86	D;.;.;.
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	D;D;D;D
M_CAP	Pathogenic	0.35	D
MetaRNN	Pathogenic	0.85	D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.1	H;.;.;.
PhyloP100		7.6
PrimateAI	Uncertain	0.76	T
PROVEAN	Uncertain	-2.6	D;.;.;.
REVEL	Pathogenic	0.68
Sift	Pathogenic	0.0	D;.;.;.
Sift4G	Pathogenic	0.0	D;.;.;.
Polyphen		1.0	D;.;.;.
Vest4		0.90
MutPred		0.72		Loss of glycosylation at S657 (P = 0.02);.;.;.;
MVP		0.99
MPC		0.31
ClinPred		1.0	D
GERP RS		5.9
Varity_R		0.86
gMVP		0.94
Mutation Taster		=29/71	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs1301895668; hg19: chr9-6558641;