Exon/intron structure and donor splice site mutation of the silent Rh50 (836G) allele. Mutation screening of the silent Rh50(836G) allele in Rh_null (YT) was performed by genomic PCR. The amplified products were each designated by the two primers used (Table 1). (A) 1.8% agarose gel electophoresis of the 11 genomic products. Note that segment 5′P2/5′P3 is upstream of and overlapping with segment 1Ps/In-1a. (B) The exon/intron structure of the silent Rh50 (836G) allele. Nucleotide sequences of the acceptor and donor splice sites are shown and compared with the consensus ones at bottom. Intronic nucleotides are denoted by lower-case letters. The g→a mutation at +1 position of intron 1 that destroys the invariant gt-element of the donor splice site is bolded and marked by an arrow.