Table 1

Evaluation of potential pathogenicity of missense variants found in the hMLH1 and hMSH2 genes

Family/ patientGene/exonDNA changeAA changeNature AA changeCons. residueFrequency controlsCosegregation with diseaseFunctional consequencesMSI (markers)IHC
MSI, microsatellite instability; IHC, immunohistochemistry; AA, amino acid; NA, not available.
Novel mutations are represented in bold type.
*Family carrying two mutations (see results).
†Despite this mutation resulting in an amino acid change, it also results in an aberrant splicing leading to exon 17 deletion, as was previously described.26
‡Three or less affected members were available per family.12
§All other affected members of the family were deceased, or unable to contact other family members.12
Fam 1MLH1 exon 17CGA to CTAR659L (aberrant splicing)†Positive charged to aliphaticYes0/50YesLoss of function ref26High (2/5)Abnormal
Fam 2MLH1 exon 16CTT to CAT L607H Neutral to chargedNo0/50YesNAStable (0/5)Normal
Fam 3MLH1 exon 8GTG to ATG V213M Non-polar to non-polarNo0/50Inconclusive‡NAStable (0/5)Normal
Fam 4MLH1 exon 16AAG to ACGK618TPositive charged to non-polarNo0/50Inconclusive‡Loss of function13151627Stable (0/5)Normal
Fam 5*MSH2 exon 6GGC to GACG322DNon-polar to negative chargedYes0/50NoNAHigh (5/5)Abnormal
Fam 6MLH1 exon 12ACGT to TGT R385C Polar to non-polarNo0/50YesNANANA
P 1MLH1 exon 16AAG to ACGK618TPositive charged to non-polarNo0/50Not possible§Loss of function13151627Stable (0/5)Normal
P 2MLH1 exon 17CCC to TCC P648S Non-polar to polarNo3/50Not possible§NAHigh (2/5)Abnormal
P 3MSH2 exon 6GGC to GACG322DNon-polar to negative chargedYes0/50Not possible§NAStable (0/5)Normal
P 4MSH2 intron 7AAG to CGG0/50Inconclusive‡NAHigh (4/5)Abnormal