Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PVS1_ModeratePM2
The NM_001048174.2(MUTYH):c.1561dupC(p.Gln521ProfsTer11) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. Q521Q) has been classified as Likely benign.
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]
MUTYH Gene-Disease associations (from GenCC):
familial adenomatous polyposis 2
Inheritance: AD, AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), Genomics England PanelApp, ClinGen, G2P
colorectal cancer
Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen
familial ovarian cancer
Inheritance: AD, AR Classification: NO_KNOWN Submitted by: ClinGen
hereditary breast carcinoma
Inheritance: AD, AR Classification: NO_KNOWN Submitted by: ClinGen
Our verdict: Uncertain_significance. The variant received 4 ACMG points.
PVS1
Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.00319 CDS is truncated, and there are 2 pathogenic variants in the truncated region.
PM2
Very rare variant in population databases, with high coverage;