Detection of OA1 intragenic deletions in males. (A) Exon 7 (top) and exon 8 (bottom) failed to amplify in two affected males III2 and V1 from family OA1-1 while the two exons amplified normally from DNA obtained from unaffected individuals (III1, III3, IV1) and a female carrier (IV2). As internal control, exon 9 of the OA1 gene has simultaneously amplified from the DNA samples of family members. (B) A deletion of exon 6, using primers 6H6F and 6H6R , was detected in the proband III1 of family OA1-2. The deletion of exon 6 was found in all affected individuals of the family (I1, III1, III3, and III4). Alternative primers were used to confirm the deletion (data not shown). M: molecular weight marker, one kilobase ladder, Gibco BRL.