Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1PM2PM5PP3_Strong
The NM_001048174.2(MUTYH):c.559G>C(p.Val187Leu) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V187M) has been classified as Likely pathogenic.
MUTYH (HGNC:7527): (mutY DNA glycosylase) This gene encodes a DNA glycosylase involved in oxidative DNA damage repair. The enzyme excises adenine bases from the DNA backbone at sites where adenine is inappropriately paired with guanine, cytosine, or 8-oxo-7,8-dihydroguanine, a major oxidatively damaged DNA lesion. The protein is localized to the nucleus and mitochondria. This gene product is thought to play a role in signaling apoptosis by the introduction of single-strand breaks following oxidative damage. Mutations in this gene result in heritable predisposition to colorectal cancer, termed MUTYH-associated polyposis (MAP). Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Apr 2017]
Verdict is Pathogenic. Variant got 10 ACMG points.
PM1
In a helix (size 16) in uniprot entity MUTYH_HUMAN there are 6 pathogenic changes around while only 0 benign (100%) in NM_001048174.2
PM2
Very rare variant in population databases, with high coverage;
PM5
Other missense variant is known to change same aminoacid residue: Variant chr1-45332621-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 184952.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
PP3
MetaRNN computational evidence supports a deleterious effect, 0.945
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change replaces valine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 215 of the MUTYH protein (p.Val215Leu). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with MUTYH-related conditions. ClinVar contains an entry for this variant (Variation ID: 1388945). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. This variant disrupts the p.Val215 amino acid residue in MUTYH. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 19032956, 19732775, 20618354; Invitae; externalcommunication). 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. -