The missense G382D mutation, already described in north and south European populations was found in the MYH gene at the homozygous state in the fourth patient with moderate AP.
Among patients with multiple adenomas, biallelic MYH mutations account for approximately 30% of APC mutation negative cases and two thirds of these carry mutations other than the "common" Y165C and G382D variants.
The lack of complementation of the hMYH variants for MutY, and the reduced activity of the Y82C and G253D E.coli enzymes, provide additional circumstantial evidence that the somatic mutations in APC, and the occurrence of FAP in Family N, are due to a reduced ability of the Y165C and G382D hMYH enzymes to recognize and repair OG:A mismatches.