chr5-151253229-A-T

Position:

• chr5-151253229-A-T

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 2P and 5B. PM2 BP4_Strong BS1_Supporting

The NM_000405.5(GM2A):​c.13A>T​(p.Met5Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000186 in 1,613,960 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another nucleotide change resulting in same amino acid change has been previously reported as Uncertain significancein ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. M5T) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000018 (0 hom.)
• Consequence: GM2A NM_000405.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: -1.58

Genes affected

GM2A (HGNC:4367): (ganglioside GM2 activator) This gene encodes a small glycolipid transport protein which acts as a substrate specific co-factor for the lysosomal enzyme beta-hexosaminidase A. Beta-hexosaminidase A, together with GM2 ganglioside activator, catalyzes the degradation of the ganglioside GM2, and other molecules containing terminal N-acetyl hexosamines. Mutations in this gene result in GM2-gangliosidosis type AB or the AB variant of Tay-Sachs disease. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Nov 2009]

ACMG classification

Verdict is Likely_benign. Variant got -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.01674211).
• BS1: Variant frequency is greater than expected in population eas. gnomad4 allele frequency = 0.0000197 (3/152262) while in subpopulation EAS AF= 0.000387 (2/5170). AF 95% confidence interval is 0.0000684. There are 0 homozygotes in gnomad4. There are 3 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GM2A	NM_000405.5	c.13A>T	p.Met5Leu	missense_variant	1/4	ENST00000357164.4
GM2A	NM_001167607.3	c.13A>T	p.Met5Leu	missense_variant	1/4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GM2A	ENST00000357164.4	c.13A>T	p.Met5Leu	missense_variant	1/4	1	NM_000405.5	P1
GM2A	ENST00000523466.5	c.127-6526A>T		intron_variant		3

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152144 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000386

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000477 AC: 12 AN: 251430 Hom.: 0 AF XY: 0.0000368 AC XY: 5 AN XY: 135898

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000489

Gnomad SAS exome AF: 0.0000980

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000185 AC: 27 AN: 1461698 Hom.: 0 Cov.: 31 AF XY: 0.0000138 AC XY: 10 AN XY: 727168

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000277

Gnomad4 SAS exome AF: 0.000151

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152262 Hom.: 0 Cov.: 32 AF XY: 0.0000403 AC XY: 3 AN XY: 74444

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000387

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

ExAC AF: 0.0000741 AC: 9

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tay-Sachs disease, variant AB Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 15, 2018	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Mar 27, 2022	This sequence change replaces methionine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 5 of the GM2A protein (p.Met5Leu). This variant is present in population databases (rs557461469, gnomAD 0.06%). This variant has not been reported in the literature in individuals affected with GM2A-related conditions. ClinVar contains an entry for this variant (Variation ID: 904953). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Not Available"; Align-GVGD: "Class C0". The leucine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.083
BayesDel_addAF	Benign	-0.49	T
BayesDel_noAF	Benign	-0.58
CADD	Benign	0.090
DANN	Benign	0.70
DEOGEN2	Benign	0.11	T
Eigen	Benign	-1.7
Eigen_PC	Benign	-1.8
FATHMM_MKL	Benign	0.050	N
LIST_S2	Benign	0.37	T
M_CAP	Benign	0.0088	T
MetaRNN	Benign	0.017	T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	0.20	N
MutationTaster	Benign	1.0	N
PrimateAI	Benign	0.46	T
PROVEAN	Benign	-0.65	N
REVEL	Benign	0.24
Sift	Benign	0.18	T
Sift4G	Benign	0.59	T
Polyphen		0.0	B
Vest4		0.18
MutPred		0.15		Loss of disorder (P = 0.1144);
MVP		0.12
MPC		0.064
ClinPred		0.097	T
GERP RS		-5.8
Varity_R		0.13
gMVP		0.43

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: rs557461469; hg19: chr5-150632790;