Frequent normal allele loss and maternal origin of the mutation shown by DNA homoduplex analysis in a severely affected patient with adenomatous polyposis coli

An atypically high frequency of loss of heterozygosity at chromosome 5q22 in small adenomas from a severely affected new mutation patient with adenomatous polyposis coli was recently reported. DNA homoduplex analysis has now been used to show that the deletion in the adenomas extends to include the APC locus and that the normal allele is lost. These data also prove the maternal origin of the mutation.