12-101764223-CTTT-CTT

Position:

• chr12-101764223-CTTT-CTT

Variant summary

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

The NM_024312.5(GNPTAB):​c.2693del​(p.Lys898SerfsTer13) variant causes a frameshift change. The variant allele was found at a frequency of 0.0000041 in 1,461,648 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: GNPTAB NM_024312.5 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5 O:1
• Conservation: PhyloP100: 4.37

Genes affected

GNPTAB (HGNC:29670): (N-acetylglucosamine-1-phosphate transferase subunits alpha and beta) This gene encodes two of three subunit types of the membrane-bound enzyme N-acetylglucosamine-1-phosphotransferase, a heterohexameric complex composed of two alpha, two beta, and two gamma subunits. The encoded protein is proteolytically cleaved at the Lys928-Asp929 bond to yield mature alpha and beta polypeptides while the gamma subunits are the product of a distinct gene (GeneID 84572). In the Golgi apparatus, the heterohexameric complex catalyzes the first step in the synthesis of mannose 6-phosphate recognition markers on certain oligosaccharides of newly synthesized lysosomal enzymes. These recognition markers are essential for appropriate trafficking of lysosomal enzymes. Mutations in this gene have been associated with both mucolipidosis II and mucolipidosis IIIA.[provided by RefSeq, May 2010]

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 12-101764223-CT-C is Pathogenic according to our data. Variant chr12-101764223-CT-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 39058.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr12-101764223-CT-C is described in Lovd as [Pathogenic]. Variant chr12-101764223-CT-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GNPTAB	NM_024312.5	c.2693del	p.Lys898SerfsTer13	frameshift_variant	13/21	ENST00000299314.12
GNPTAB	XM_011538731.3	c.2612del	p.Lys871SerfsTer13	frameshift_variant	13/21
GNPTAB	XM_006719593.4	c.2693del	p.Lys898SerfsTer13	frameshift_variant	13/19

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GNPTAB	ENST00000299314.12	c.2693del	p.Lys898SerfsTer13	frameshift_variant	13/21	1	NM_024312.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000410 AC: 6 AN: 1461648 Hom.: 0 Cov.: 32 AF XY: 0.00000550 AC XY: 4 AN XY: 727132

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: 0.00000450

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Pseudo-Hurler polydystrophy;C2673377:Mucolipidosis type II Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Apr 04, 2018	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Mar 21, 2023	For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 39058). This premature translational stop signal has been observed in individual(s) with mucolipidosis III (PMID: 19197337). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change creates a premature translational stop signal (p.Lys898Serfs*13) in the GNPTAB gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in GNPTAB are known to be pathogenic (PMID: 19617216, 25107912). -

Pseudo-Hurler polydystrophy Pathogenic:1 Other:1

not provided, no classification provided	literature only	GeneReviews	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jul 28, 2016	Variant summary: The GNPTAB c.2693delA (p.Lys898Serfs) variant results in a premature termination codon, predicted to cause a truncated or absent GNPTAB protein due to nonsense mediated decay, which are commonly known mechanisms for disease. The variant of interest was not found in controls (ExAC, 1000 Gs or ESP) and has been reported in one affected individual who was diagnosed with ML III and was compound heterozygous for the variant of interest and an exon 2 duplication. GeneReviews classifies the variant as "pathogenic." Therefore, taking all available lines of evidence into consideration the varinat of interest has been classified as Pathogenic. -

Mucolipidosis Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Department of Genetics and Endocrinology, Guangzhou Women and Children’s Medical Center

-

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Kariminejad - Najmabadi Pathology & Genetics Center

Jul 10, 2021

- -

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: rs281864999; hg19: chr12-102158001;