rs1318217031

Positions:

• chr8-43182174-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_152419.3(HGSNAT):​c.1042G>A​(p.Val348Met) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. V348V) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 31)
• Consequence: HGSNAT NM_152419.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.86

Genes affected

HGSNAT (HGNC:26527): (heparan-alpha-glucosaminide N-acetyltransferase) This gene encodes a lysosomal acetyltransferase, which is one of several enzymes involved in the lysosomal degradation of heparin sulfate. Mutations in this gene are associated with Sanfilippo syndrome C, one type of the lysosomal storage disease mucopolysaccaridosis III, which results from impaired degradation of heparan sulfate. [provided by RefSeq, Jan 2009]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.903

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HGSNAT	NM_152419.3	c.1042G>A	p.Val348Met	missense_variant	11/18	ENST00000379644.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HGSNAT	ENST00000379644.9	c.1042G>A	p.Val348Met	missense_variant	11/18	2	NM_152419.3	P3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 31

Bravo AF: 0.0000151

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Mucopolysaccharidosis, MPS-III-C Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Undiagnosed Diseases Network, NIH

Aug 09, 2017

Two heterozygous variants of unknown significance, c.1042G>A (p.V348M) and c.1267G>T (p.G423W) were detected in the HGSNAT gene in this individual. Whole exome sequencing and Sanger confirmation showed that the father is heterozygous for the p.V348M change, and the mother is heterozygous for the p.G423W change. Our data indicate that the two changes in HGSNAT are in trans (compound heterozygous) configuration. -

Mucopolysaccharidosis, MPS-III-C;C4225287:Retinitis pigmentosa 73 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Oct 03, 2023

This sequence change replaces valine, which is neutral and non-polar, with methionine, which is neutral and non-polar, at codon 348 of the HGSNAT protein (p.Val348Met). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with HGSNAT-related conditions. ClinVar contains an entry for this variant (Variation ID: 522867). 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 HGSNAT 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
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.46
CADD	Pathogenic	27
DANN	Uncertain	1.0
Eigen	Pathogenic	0.95
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Pathogenic	0.98	D;D;D
M_CAP	Uncertain	0.16	D
MetaRNN	Pathogenic	0.90	D;D;D
MetaSVM	Pathogenic	1.0	D
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.74	T
PROVEAN	Uncertain	-2.7	D;D;D
REVEL	Pathogenic	0.89
Sift	Uncertain	0.0030	D;D;D
Sift4G	Uncertain	0.0020	D;D;D
Vest4		0.95
MVP		0.94
MPC		0.52
ClinPred		1.0	D
GERP RS		5.1
gMVP		0.82

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs1318217031; hg19: chr8-43037317;