Our verdict is Benign. Variant got -7 ACMG points: 2P and 9B. PM2BP4_StrongBP6BS1
The NM_017739.4(POMGNT1):c.421-7C>A variant causes a splice region, splice polypyrimidine tract, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000496 in 1,614,140 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
POMGNT1 (HGNC:19139): (protein O-linked mannose N-acetylglucosaminyltransferase 1 (beta 1,2-)) This gene encodes a type II transmembrane protein that resides in the Golgi apparatus. It participates in O-mannosyl glycosylation and is specific for alpha linked terminal mannose. Mutations in this gene may be associated with muscle-eye-brain disease and several congenital muscular dystrophies. Alternatively spliced transcript variants that encode different protein isoforms have been described. [provided by RefSeq, Feb 2014]
Very rare variant in population databases, with high coverage;
BP4
Computational evidence support a benign effect (BayesDel_noAF=-0.78).
BP6
Variant 1-46195931-G-T is Benign according to our data. Variant chr1-46195931-G-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 198222.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=3, Uncertain_significance=5, Benign=1}.
BS1
Variant frequency is greater than expected in population amr. gnomad4_exome allele frequency = 0.000502 (734/1461854) while in subpopulation AMR AF= 0.00221 (99/44722). AF 95% confidence interval is 0.00186. There are 1 homozygotes in gnomad4_exome. There are 342 alleles in male gnomad4_exome subpopulation. Median coverage is 31. This position pass quality control queck.
Uncertain significance, criteria provided, single submitter
clinical testing
Athena Diagnostics
Aug 25, 2022
- -
Uncertain significance, criteria provided, single submitter
clinical testing
Eurofins Ntd Llc (ga)
Feb 09, 2018
- -
Likely benign, criteria provided, single submitter
clinical testing
CeGaT Center for Human Genetics Tuebingen
Mar 01, 2024
POMGNT1: BP4 -
not specified Uncertain:1Benign:1
Benign, criteria provided, single submitter
clinical testing
GeneDx
Sep 04, 2015
This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -
Uncertain significance, criteria provided, single submitter
clinical testing
Women's Health and Genetics/Laboratory Corporation of America, LabCorp
Mar 08, 2024
Variant summary: POMGNT1 c.421-7C>A alters a non-conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Consensus agreement among computation tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 0.00053 in 251282 control chromosomes. This frequency is not significantly higher than estimated for a pathogenic variant in POMGNT1 causing Limb-Girdle Muscular Dystrophy, Autosomal Recessive (0.00053 vs 0.00072), allowing no conclusion about variant significance. To our knowledge, no occurrence of c.421-7C>A in individuals affected with Limb-Girdle Muscular Dystrophy, Autosomal Recessive and no experimental evidence demonstrating its impact on protein function have been reported. ClinVar contains an entry for this variant (Variation ID: 198222). Based on the evidence outlined above, the variant was classified as VUS-possibly benign. -
Autosomal recessive limb-girdle muscular dystrophy type 2O Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
Illumina Laboratory Services, Illumina
Jan 12, 2018
This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -
Congenital Muscular Dystrophy, alpha-dystroglycan related Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
Illumina Laboratory Services, Illumina
Jan 12, 2018
This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -
Muscular dystrophy-dystroglycanopathy (congenital with intellectual disability), type B3;C3150417:Autosomal recessive limb-girdle muscular dystrophy type 2O Benign:1
Likely benign, criteria provided, single submitter
clinical testing
Invitae
Jan 31, 2024
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POMGNT1-related disorder Benign:1
Likely benign, criteria provided, single submitter
clinical testing
PreventionGenetics, part of Exact Sciences
Mar 16, 2022
This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -