FREQUENT NORMAL ALLELE LOSS AND MATERNAL ORIGIN OF THE MUTATION SHOWNBY DNA HOMODUPLEX ANALYSIS IN A SEVERELY AFFECTED PATIENT WITH ADENOMATOUS POLYPOSIS-COLI

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