rs1555621448

Variant names:

• chr17-42536491-G-GC
• rs1555621448
• NM_000263.4:c.220dupC

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000263.4(NAGLU):​c.220dupC​(p.Arg74ProfsTer118) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. R74R) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 33)
• Consequence: NAGLU NM_000263.4 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 0.206
• Publications: 0 publications found

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]

NAGLU Gene-Disease associations (from GenCC):

• mucopolysaccharidosis type 3B

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: ClinGen, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), G2P, Orphanet, Myriad Women’s Health
• Charcot-Marie-Tooth disease axonal type 2V

  Inheritance: AD Classification: SUPPORTIVE, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), Orphanet

ENSG00000266929 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 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 17-42536491-G-GC is Pathogenic according to our data. Variant chr17-42536491-G-GC is described in ClinVar as Pathogenic. ClinVar VariationId is 554243.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000263.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	NAGLU	NM_000263.4	MANE Select	c.220dupC	p.Arg74ProfsTer118	frameshift	Exon 1 of 6	NP_000254.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	NAGLU	ENST00000225927.7	TSL:1 MANE Select	c.220dupC	p.Arg74ProfsTer118	frameshift	Exon 1 of 6	ENSP00000225927.1
	NAGLU	ENST00000586516.5	TSL:2	c.-33_-32insC		upstream_gene	N/A	ENSP00000467135.1
	NAGLU	ENST00000591587.1	TSL:5	c.-39_-38insC		upstream_gene	N/A	ENSP00000467836.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Mucopolysaccharidosis, MPS-III-B Pathogenic:1

Oct 02, 2017

Counsyl

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com.

not provided Pathogenic:1

Aug 04, 2023

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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: 11286389)

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

Mar 22, 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.Arg74Profs*118) in the NAGLU gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in NAGLU are known to be pathogenic (PMID: 9832037, 10094189, 16151907). 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 B (PMID: 11286389). This variant is also known as 220insC. ClinVar contains an entry for this variant (Variation ID: 554243). For these reasons, this variant has been classified as Pathogenic.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		0.21
Mutation Taster		=9/191	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs1555621448; hg19: chr17-40688509;