chr8-43193844-G-A

Position:

• chr8-43193844-G-A

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_Moderate PM2 PP5_Very_Strong

The NM_152419.3(HGSNAT):​c.1464+1G>A variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000198 in 1,461,092 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.000020 (0 hom.)
• Consequence: HGSNAT NM_152419.3 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 9.46

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 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.045073375 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 8-43193844-G-A is Pathogenic according to our data. Variant chr8-43193844-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 96502.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr8-43193844-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HGSNAT	NM_152419.3	c.1464+1G>A		splice_donor_variant, intron_variant		ENST00000379644.9	NP_689632.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
HGSNAT	ENST00000379644.9	c.1464+1G>A		splice_donor_variant, intron_variant		2	NM_152419.3	ENSP00000368965.4
HGSNAT	ENST00000521576.1	c.615+1G>A		splice_donor_variant, intron_variant		2		ENSP00000429029.1
HGSNAT	ENST00000524016.5	c.567+1G>A		splice_donor_variant, intron_variant		4		ENSP00000428322.1
HGSNAT	ENST00000520678.1	n.398G>A		non_coding_transcript_exon_variant	4/4	3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000803 AC: 2 AN: 249132 Hom.: 0 AF XY: 0.00000740 AC XY: 1 AN XY: 135164

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000177

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000198 AC: 29 AN: 1461092 Hom.: 0 Cov.: 30 AF XY: 0.0000220 AC XY: 16 AN XY: 726856

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: 0.0000252

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 33

ExAC AF: 0.00000828 AC: 1

EpiCase AF: 0.0000545

EpiControl AF: 0.000119

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Mucopolysaccharidosis, MPS-III-C Pathogenic:2

Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Jun 24, 2021	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Dec 21, 2017	- -

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

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Sep 19, 2023	This sequence change affects a donor splice site in intron 14 of the HGSNAT gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in HGSNAT are known to be pathogenic (PMID: 17033958, 19479962). This variant is present in population databases (rs398124545, gnomAD 0.002%). Disruption of this splice site has been observed in individuals with mucopolysaccharidosis type IIIC (PMID: 17397050, 28981474). ClinVar contains an entry for this variant (Variation ID: 96502). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Jan 11, 2022	- -

not provided Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Dec 03, 2021	Reported with another HGSNAT variant in a patient with retinitis pigmentosa in published literature, but it is not known whether the variants occurred on the same (in cis) or on different (in trans) chromosomes (Comander et al., 2017); Canonical splice site variant predicted to result in an in-frame deletion of a critical region; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 25525159, 28981474, 17397050, 34047372) -
Pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Jun 18, 2013	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.61	D
BayesDel_noAF	Pathogenic	0.41
CADD	Pathogenic	33
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
GERP RS		5.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.96
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.99		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs398124545; hg19: chr8-43048987;