rs121907954

Variant names:

• chr15-72350518-C-G
• rs121907954
• NM_000520.6:c.805G>C

Your query was ambiguous. Multiple possible variants found:

• chr15-72350518-C-G
• chr15-72350518-C-T

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000520.6(HEXA):​c.805G>C​(p.Gly269Arg) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,698 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 15/24 in silico tools predict a damaging outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G269S) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: HEXA NM_000520.6 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 7.81
• Publications: 72 publications found

Genes affected

HEXA (HGNC:4878): (hexosaminidase subunit alpha) This gene encodes a member of the glycosyl hydrolase 20 family of proteins. The encoded preproprotein is proteolytically processed to generate the alpha subunit of the lysosomal enzyme beta-hexosaminidase. This enzyme, together with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules containing terminal N-acetyl hexosamines. Mutations in this gene lead to an accumulation of GM2 ganglioside in neurons, the underlying cause of neurodegenerative disorders termed the GM2 gangliosidoses, including Tay-Sachs disease (GM2-gangliosidosis type I). Alternative splicing results in multiple transcript variants, at least one of which encodes a preproprotein that is proteolytically processed. [provided by RefSeq, Jan 2016]

HEXA Gene-Disease associations (from GenCC):

• Tay-Sachs disease

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Myriad Women’s Health, Genomics England PanelApp, G2P, Labcorp Genetics (formerly Invitae), ClinGen

ENSG00000261460 (HGNC:58304):

ENSG00000260729 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_000520.6
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr15-72350518-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 3898.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.
• PP5: Variant 15-72350518-C-G is Pathogenic according to our data. Variant chr15-72350518-C-G is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 375357.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HEXA	NM_000520.6	c.805G>C	p.Gly269Arg	missense_variant, splice_region_variant	Exon 7 of 14	ENST00000268097.10	NP_000511.2
HEXA	NM_001318825.2	c.838G>C	p.Gly280Arg	missense_variant, splice_region_variant	Exon 7 of 14		NP_001305754.1
HEXA	NR_134869.3	n.847G>C		splice_region_variant, non_coding_transcript_exon_variant	Exon 7 of 11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HEXA	ENST00000268097.10	c.805G>C	p.Gly269Arg	missense_variant, splice_region_variant	Exon 7 of 14	1	NM_000520.6	ENSP00000268097.6
ENSG00000260729	ENST00000379915.4	n.413-4193G>C		intron_variant	Intron 3 of 15	2		ENSP00000478716.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461698 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727154

African (AFR) AF: 0.00 AC: 0 AN: 33472

American (AMR) AF: 0.00 AC: 0 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: 0.0000116 AC: 1 AN: 86250

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53412

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5658

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111966

Other (OTH) AF: 0.00 AC: 0 AN: 60380

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tay-Sachs disease Pathogenic:3

Nov 26, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the c.805 nucleotide in the HEXA gene. Other variant(s) that disrupt this nucleotide have been determined to be pathogenic (PMID: 2522679, 20363167). This suggests that this nucleotide is clinically significant, and that variants that disrupt this position are likely to be disease-causing. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). ClinVar contains an entry for this variant (Variation ID: 375357). This missense change has been observed in individual(s) with Tay–Sachs disease (PMID: 27896118). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 269 of the HEXA protein (p.Gly269Arg). This variant also falls at the last nucleotide of exon 7, which is part of the consensus splice site for this exon. -

Aug 22, 2023

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: HEXA c.805G>C (p.Gly269Arg) results in a non-conservative amino acid change located in the Glycoside hydrolase family 20, catalytic domain (IPR015883) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. Several computational tools predict a significant impact on normal splicing: Three predict the variant weakens the canonical 5' donor site. However, these predictions have yet to be confirmed by functional studies. The variant was absent in 251438 control chromosomes (gnomAD). c.805G>C has been reported in the literature in one individual affected with Tay-Sachs Disease and one individual affected with central nervous system white matter abnormalities (examples: Sheth _2014 and Kaur_2021). 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. A different variant affecting the same codon (c.805G>A , p.Gly269Ser) is classified pathogenic internally and in ClinVar (CV ID 3898). This suggests that this residue may be clinically significant. The following publications have been ascertained in the context of this evaluation (PMID: 34302356, 27896118). One submitter has cited clinical-significance assessments for this variant to ClinVar after 2014 and has classified the variant as likely pathogenic. Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Dec 18, 2012

Foundation for Research in Genetics and Endocrinology, FRIGE's Institute of Human Genetics

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: research

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.92
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	34
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.96	D;.;D
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.98
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.92	D;D;D
M_CAP	Pathogenic	0.36	D
MetaRNN	Pathogenic	0.95	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.6	H;.;.
PhyloP100		7.8
PrimateAI	Uncertain	0.78	T
PROVEAN	Pathogenic	-7.6	D;D;D
REVEL	Pathogenic	0.98
Sift	Uncertain	0.0010	D;D;D
Sift4G	Uncertain	0.0020	D;D;D
Polyphen		1.0	D;.;.
Vest4		0.94
MutPred		0.75		Gain of solvent accessibility (P = 0.0055);.;Gain of solvent accessibility (P = 0.0055);
MVP		1.0
MPC		0.82
ClinPred		1.0	D
GERP RS		5.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.1
Varity_R		0.97
gMVP		0.96
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.030		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: rs121907954; hg19: chr15-72642859;