8-43161468-C-CT

Position:

• chr8-43161468-C-CT

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_152419.3(HGSNAT):​c.525dupT​(p.Val176fs) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000206 in 1,459,690 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: HGSNAT NM_152419.3 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: -5.34

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 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 8-43161468-C-CT is Pathogenic according to our data. Variant chr8-43161468-C-CT is described in ClinVar as [Pathogenic]. Clinvar id is 1235.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HGSNAT	NM_152419.3	c.525dupT	p.Val176fs	frameshift_variant	5/18	ENST00000379644.9	NP_689632.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
HGSNAT	ENST00000379644.9	c.525dupT	p.Val176fs	frameshift_variant	5/18	2	NM_152419.3	ENSP00000368965.4
HGSNAT	ENST00000520704.1	n.375dupT		non_coding_transcript_exon_variant	5/10	1		ENSP00000429109.1
HGSNAT	ENST00000517319.1	n.*94dupT		non_coding_transcript_exon_variant	4/5	4		ENSP00000430032.1
HGSNAT	ENST00000517319.1	n.*94dupT		3_prime_UTR_variant	4/5	4		ENSP00000430032.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000206 AC: 3 AN: 1459690 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 726078

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Mucopolysaccharidosis, MPS-III-C;C4225287:Retinitis pigmentosa 73 Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Jul 23, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Nov 14, 2023	This sequence change creates a premature translational stop signal (p.Val176Cysfs*16) in the HGSNAT gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in HGSNAT are known to be pathogenic (PMID: 17033958, 19479962). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with HGSNAT-related conditions (PMID: 18518886). ClinVar contains an entry for this variant (Variation ID: 1235). For these reasons, this variant has been classified as Pathogenic. -

Mucopolysaccharidosis, MPS-III-C Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Aug 01, 2008

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

May 05, 2022

Frameshift 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: 18518886) -

Computational scores

Source: dbNSFP v4.3

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: rs483352895; hg19: chr8-43016611;