ClinVar

Description

The c.1895+1G>T variant in POMGNT1 has been previously reported in eight individuals with muscular dystrophy-dystroglycanopathy (PMID: 32115343, PMID: 29555514, PMID: 28688748, PMID: 22323514, PMID: 19299310, PMID: 15466003, PMID: 22554691, PMID: 28424332), and has been identified in 0.012% (15/128292) non-Finnish European chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP ID: rs386834024). Although this variant has been seen in the general population in a heterozygous state, its frequency is not high enough to rule out a pathogenic role. This variant has also been reported in ClinVar (Variation ID#:56593) and has been interpreted as pathogenic by Illumina (most recent interpretation; previously interpreted as VUS [2016] and likely pathogenic [2016]), Ambry Genetics, Centre for Mendelian Genomics,University Medical Centre Ljubljana, Broad Institute Rare Disease Group,GeneDx, Invitae, Juha Muilu Group; Institute for Molecular Medicine Finland (FIMM), Myriad Women's Health, Inc., Natera, Inc, PerkinElmer Genomics, and Counsyl. Of these eight affected individuals, one was a compound heterozygote who carried a pathogenic variant with unknown phase (PMID: 29555514) and one was a compound heterozygote who carried a likely pathogenic variant with unknown phase (PMID: 22323514), which increases the likelihood that the c.1895+1G>T variant is pathogenic. The variant was shown by RT-PCR analysis (PMID: 22554691) and muscle RNAseq of patient tissue (PMID: 28424332) to alter splicing and lead to intron retention between exons 21 and 22. This variant is located in the 5’ splice region. Computational tools predict a splicing impact, though this information is not predictive enough to determine pathogenicity. Loss of function of the POMGNT1 gene 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_Moderate, PS3, PM3 (Richards 2015).