rs1554537841

Positions:

• chr8-43197900-C-G
• chr8-43197900-C-T

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.1674C>G​(p.Tyr558*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,674 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 Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: HGSNAT NM_152419.3 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 0.507

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]

HGSNAT (HGNC:):

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 8-43197900-C-G is Pathogenic according to our data. Variant chr8-43197900-C-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 553553.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr8-43197900-C-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HGSNAT	NM_152419.3	c.1674C>G	p.Tyr558*	stop_gained	17/18	ENST00000379644.9	NP_689632.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
HGSNAT	ENST00000379644.9	c.1674C>G	p.Tyr558*	stop_gained	17/18	2	NM_152419.3	ENSP00000368965.4
HGSNAT	ENST00000519705.1	n.990C>G		non_coding_transcript_exon_variant	3/4	1
HGSNAT	ENST00000521576.1	c.825C>G	p.Tyr275*	stop_gained	8/9	2		ENSP00000429029.1
HGSNAT	ENST00000523989.1	n.1987C>G		non_coding_transcript_exon_variant	2/2	4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461674 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 727116

Gnomad4 AFR exome AF: 0.0000299

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Mucopolysaccharidosis, MPS-III-C Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Counsyl

Aug 31, 2017

- -

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

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 21, 2023

This variant is not present in population databases (gnomAD no frequency). For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 553553). This premature translational stop signal has been observed in individual(s) with mucopolysaccharidosis type IIIC (PMID: 19479962). This sequence change creates a premature translational stop signal (p.Tyr558*) 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). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Uncertain	0.55
Eigen_PC	Uncertain	0.39
FATHMM_MKL	Uncertain	0.92	D
Vest4		0.91
GERP RS		2.8

Splicing

Name	Calibrated prediction	Score	Prediction
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

Publications

LitVar

Other links and lift over

dbSNP: rs1554537841; hg19: chr8-43053043;