17-42543603-C-T

Variant names:

• chr17-42543603-C-T
• rs1244655820
• NM_000263.4:c.1597C>T

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PVS1_Strong PM2 PP5_Very_Strong

The NM_000263.4(NAGLU):​c.1597C>T​(p.Arg533*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000186 in 1,612,976 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 (★★).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: NAGLU NM_000263.4 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 1.12

Genes affected

NAGLU (HGNC:7632): (N-acetyl-alpha-glucosaminidase) This gene encodes an enzyme that degrades heparan sulfate by hydrolysis of terminal N-acetyl-D-glucosamine residues in N-acetyl-alpha-D-glucosaminides. Defects in this gene are the cause of mucopolysaccharidosis type IIIB (MPS-IIIB), also known as Sanfilippo syndrome B. This disease is characterized by the lysosomal accumulation and urinary excretion of heparan sulfate. [provided by RefSeq, Jul 2008]

ENSG00000266929 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 14 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. There are 19 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 17-42543603-C-T is Pathogenic according to our data. Variant chr17-42543603-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 495784.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
NAGLU	NM_000263.4	c.1597C>T	p.Arg533*	stop_gained	Exon 6 of 6	ENST00000225927.7	NP_000254.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NAGLU	ENST00000225927.7	c.1597C>T	p.Arg533*	stop_gained	Exon 6 of 6	1	NM_000263.4	ENSP00000225927.1
NAGLU	ENST00000591587.1	c.*566C>T		3_prime_UTR_variant	Exon 4 of 4	5		ENSP00000467836.1
ENSG00000266929	ENST00000585572.1	n.379+4848C>T		intron_variant	Intron 3 of 4	4
NAGLU	ENST00000592454.1	c.*440C>T		downstream_gene_variant		2		ENSP00000468665.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152262 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000654

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1460714 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 726658

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152262 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74402

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.0000654

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Mucopolysaccharidosis, MPS-III-B Pathogenic:2

Apr 28, 2017

Illumina Laboratory Services, Illumina

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The NAGLU c.1597C>T (p.Arg533Ter) variant is a stop-gained variant that is predicted to result in premature termination of the protein. The p.Arg533Ter variant has been reported in one study in which it was found in two individuals with mucopolysaccharidosis type III, specifically type IIIB, including in one who carried the variant in a homozygous state and one who carried the variant in a compound heterozygous state (Mangas et al. 2008). The p.Arg533Ter variant was absent from 50 unrelated controls and is not found in the 1000 Genomes Project, the Exome Sequencing Project, or the Exome Aggregation Consortium in a region of good sequence coverage so the variant is presumed to be rare. Characterization of cell lines derived from the two patients showed significantly reduced mRNA levels and enzymatic activity (Mangas et al. 2008). Based on the evidence and the potential impact of stop-gained variants, the p.Arg533Ter variant is classified as likely pathogenic for mucopolysaccharidosis, type III. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -

Dec 30, 2017

Department Of Genetics, Sultan Qaboos University Hospital, Sultan Qaboos University

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: curation

- -

Inborn genetic diseases Pathogenic:1

Aug 27, 2021

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1597C>T (p.R533*) alteration, located in exon 6 (coding exon 6) of the NAGLU gene, consists of a C to T substitution at nucleotide position 1597. This changes the amino acid from an arginine (R) to a stop codon at amino acid position 533. This alteration occurs at the 3' terminus of the NAGLU gene, is not expected to trigger nonsense-mediated mRNA decay, and impacts the last 28% (210/743 amino acids) of the protein. Premature stop codons are typically deleterious in nature and the impacted region is critical for protein function (Ambry internal data). This variant was not reported in population-based cohorts in the Genome Aggregation Database (gnomAD). This mutation has been reported in the homozygous and compound heterozygous states in patients with biochemically confirmed mucopolysaccharidosis type III. Patient cell lines demonstrated significantly decreased levels of mRNA and enzymatic activity (Mangas, 2008). Based on the available evidence, this alteration is classified as pathogenic. -

not provided Pathogenic:1

Jul 01, 2019

Revvity Omics, Revvity

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mucopolysaccharidosis, MPS-III-B;C5569050:Charcot-Marie-Tooth disease axonal type 2V Pathogenic:1

Jul 06, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Arg533*) in the NAGLU gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 211 amino acid(s) of the NAGLU protein. This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with mucopolysaccharidosis type III (PMID: 18218046). ClinVar contains an entry for this variant (Variation ID: 495784). For these reasons, this variant has been classified as Pathogenic. -

Sanfilippo syndrome Pathogenic:1

Dec 23, 2016

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: The NAGLU c.1597C>T (p.Arg533*) variant results in a premature termination codon, predicted to cause a truncated or absent NAGLU protein due to nonsense mediated decay (NMD), which are commonly known mechanisms for disease. Functional analysis shows that this variant escapes NMD (Mangas_2008). Thus, based on its location and effect, it is expected to delete a substantial part of Alpha-N-acetylglucosaminidase, C-terminal domain (residue 474 733) (InterPro). Truncations downstream of this position (e.g. p.Arg626Ter, c.1944dupG, etc.) have been reported in MPS IIIB patients and classified as pathogenic by the labs in ClinVar. This variant is absent in 114224 control chromosomes from ExAC. In literature, this variant has been reported in two Portuguese MPS IIIB patients: one patient with severe disease was homozygous for the variant and other patient with mild disease was compound heterozygous for this variant and R643C (Mangas_2008). Functional analysis using patient cells from the homozygote showed null enzymatic activity. Taken together, this variant is classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.66	D
BayesDel_noAF	Pathogenic	0.49
CADD	Pathogenic	36
DANN	Uncertain	1.0
Eigen	Uncertain	0.39
Eigen_PC	Benign	0.15
FATHMM_MKL	Benign	0.72	D
Vest4		0.58
GERP RS		3.7

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: rs1244655820; hg19: chr17-40695621;