Description
Variant summary: MSH6 c.866_867delinsAA (p.Gly289Glu) results in a non-conservative amino acid change in the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. The variant allele (comprised of 2 individual constituent variants 2-48025989-C-A and 2-48025988-G-A in cis; GRC37 hg19) was found at a frequency of 8.5e-05 in 282558 control chromosomes, predominantly at a frequency of 0.00019 within the Non-Finnish European subpopulation in the gnomAD database. The observed variant frequency within Non-Finnish European control individuals in the gnomAD database is approximately 1.34 fold of the estimated maximal expected allele frequency for a pathogenic variant in MSH6 causing Hereditary Nonpolyposis Colorectal Cancer phenotype (0.00014). c.866_867delinsAA has been reported in the literature in individuals affected with HNPCC, colorectal adenomas, colorectal cancer and breast cancer (example, Colley_2005, Devlin_2008, Baglietto_2010, Caminsky_2016). These reports do not provide unequivocal conclusions about association of the variant with Hereditary Nonpolyposis Colorectal Cancer/Lynch Syndrome. At-least two co-occurrences with pathogenic variants have been observed internally (APC c.4987G>T, p.Glu1663X; CHEK2 c.1555C>T, p.Arg519X), providing supporting evidence for a benign role. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 20028993, 26898890, 16010685, 18269114, 31422818, 26333163, 23621914). ClinVar contains an entry for this variant (Variation ID: 89572). Based on the evidence outlined above, the variant was classified as likely benign.
# | Sample | Method | Observation |
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Origin | Affected | Number tested | Tissue | Purpose | Method | Individuals | Allele frequency | Families | Co-occurrences |
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1 | germline | unknown | not provided | not provided | not provided | | not provided | not provided | not provided | not provided |