Mutation of the RH50 gene in patient AL and its inheritance in the family. (A) The G nucleotide of the 5′ donor splice-site of intron 1 in the control sequence is replaced by an A in AL, thus creating a new Rca I site. (B) Tree of family L andRca I restriction pattern of the genomic PCR products are shown. The 316-bp PCR product (see Materials and Methods) encompassing the splice-site mutation shown in (A) was cleaved into two 158-bp fragments in AL, demonstrating the homozygosity of the mutation in this patient. As expected, the product from a control DNA was uncut. The arrow shows the Rh_null proposita AL. The initials of each family member are indicated. Intron and exon sequences are in lowercase and uppercase, respectively.