ClinVar

Description

The MSH2 p.His839Arg variant was identified in 3 of 428 proband chromosomes (frequency: 0.007) from individuals or families with Lynch syndrome and was not identified in 400 control chromosomes from healthy individuals (Tang 2009, Wang 2006, Yuan 2004). The variant was also identified in dbSNP (ID: rs63750027) as "With Uncertain significance allele" and in ClinVar (classified as likely benign by Invitae; and as uncertain significance by InSiGHT, Ambry Genetics, GeneDx and one other submitter). The variant was not identified in UMD-LSDB. The variant was identified in 8 of 277214 chromosomes at a frequency of 0.00003 (Genome Aggregation Database Feb 27, 2017). The variant was observed in the following populations: Other in 1 of 6468 chromosomes (freq: 0.0002) and East Asian in 7 of 18866 chromosomes (freq: 0.0004), but was not observed in the African, Latino, European, Ashkenazi Jewish, Finnish, or South Asian populations. Functional and structural analysis of the variant showed reduced protein expression as well as altered RNA structure and MutSα dimerization (Arora 2017). The p.His839 residue is conserved in mammals and computational analyses (PolyPhen-2, SIFT, AlignGVGD, BLOSUM, MutationTaster) provide inconsistent predictions regarding the impact to the protein; this information is not very predictive of pathogenicity. The variant occurs outside of the splicing consensus sequence and in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer) do not predict a difference in splicing. In summary, based on the above information, the clinical significance of this variant cannot be determined with certainty at this time. This variant is classified as a variant of uncertain significance.