Submissions for variant NM_017739.4(POMGNT1):c.263del (p.Pro88fs)

dbSNP: rs1557677980

Total submissions: 2

Submitter	RCV	SCV	Clinical significance	Condition	Last evaluated	Review status	Method	Comment
Labcorp Genetics (formerly Invitae), Labcorp	RCV001922845	SCV002170035	pathogenic	Autosomal recessive limb-girdle muscular dystrophy type 2O; Muscular dystrophy-dystroglycanopathy (congenital with intellectual disability), type B3	2022-07-21	criteria provided, single submitter	clinical testing	This variant has not been reported in the literature in individuals affected with POMGNT1-related conditions. For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 1399654). This variant is present in population databases (no rsID available, gnomAD 0.006%). This sequence change creates a premature translational stop signal (p.Pro88Hisfs*14) in the POMGNT1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in POMGNT1 are known to be pathogenic (PMID: 19299310, 20816175, 21447391, 26908613, 27391550).
Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard	RCV002555611	SCV003761203	likely pathogenic	Muscular dystrophy-dystroglycanopathy	2023-01-24	criteria provided, single submitter	curation	The p.Pro88fs variant in POMGNT1 has not been previously reported in the literature in individuals with POMGNT1-associated muscular dystrophy-dystroglycanopathy, but has been identified in 0.006% (2/34590) of Latino/Admixed American chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP ID: rs1557677980). Although this variant has been seen in the general population in a heterozygous state, its frequency is low enough to be consistent with a recessive carrier frequency. It is of note that this variant occurs in a homopolymer repeat, which could indicate that it exists as an artifact from sequencing. However, disease-causing variants have been reported in homopolymer regions, so this is not enough to rule out a pathogenic role. This variant has also been reported in ClinVar (Variation ID#1399654) and has been interpreted as pathogenic by Invitae. This variant is predicted to cause a frameshift, which alters the protein’s amino acid sequence beginning at position 88 and leads to a premature termination codon 14 amino acids downstream. This alteration is then predicted to lead to a truncated or absent protein. Loss of function is an established disease mechanism in autosomal recessive POMGNT1-associated muscular dystrophy-dystroglycanopathy. In summary, although additional studies are required to fully establish its clinical significance, this variant is likely pathogenic for POMGNT1-associated muscular dystrophy-dystroglycanopathy. ACMG/AMP Criteria applied: PVS1, PM2 (Richards 2015).