Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong
The NM_001048174.2(MUTYH):c.228C>G(p.Tyr76*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. 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 Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. Y76Y) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.
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 18 ACMG points.
PVS1
Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
PM2
Very rare variant in population databases, with high coverage;
PP5
Variant 1-45333449-G-C is Pathogenic according to our data. Variant chr1-45333449-G-C is described in ClinVar as [Pathogenic]. Clinvar id is 1455088.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
Review Status: criteria provided, single submitter
Collection Method: clinical testing
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Sep 14, 2022
Labcorp Genetics (formerly Invitae), Labcorp
Significance: Pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing
For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This sequence change creates a premature translational stop signal (p.Tyr104*) in the MUTYH gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in MUTYH are known to be pathogenic (PMID: 18534194, 20663686). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with MUTYH-associated polyposis (MAP) (PMID: 26414517). This variant is also known as c.303C>G (p.Tyr101X). ClinVar contains an entry for this variant (Variation ID: 1455088). -