ClinVar Genomic variation as it relates to human health

The p.A176T variant (also known as c.526G>A), located in coding exon 2 of the MEN1 gene, results from a G to A substitution at nucleotide position 526. The alanine at codon 176 is replaced by threonine, an amino acid with similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear.

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge; This variant is associated with the following publications: (PMID: 9989505, 28454119, 23648481, 22090276, 11221882, 12509449, 9215689)

This missense variant replaces alanine with threonine at codon 176 of the MEN1 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant nor has this variant been reported as a germline mutation in individuals affected with hereditary cancer in the literature. A different missense variant at this codon, p.Ala176Pro, is considered disease-causing in ClinVar (variation ID 200975) and has been detected in a family affected with MEN1 (PMID: 9215689) and functional studies have shown the p.Ala176Pro variant to be unstable and exhibited loss of function in the binding and regulation of JunD and in homology-directed repair and response to DNA damage (PMID: 9989505, 11221882, 12509449, 22090276, 23648481). This variant has been identified in 1/251222 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance.

This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 176 of the MEN1 protein (p.Ala176Thr). This variant is present in population databases (no rsID available, gnomAD 0.003%). This variant has not been reported in the literature in individuals affected with MEN1-related conditions. ClinVar contains an entry for this variant (Variation ID: 825603). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt MEN1 protein function with a positive predictive value of 95%. This variant disrupts the p.Ala176 amino acid residue in MEN1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 9215689, 9989505, 11221882, 12509449, 22090276, 23648481; Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance.