Sequencing analysis of RHD intron 7 and 9.

Whole length of RHD introns 7 and 9 of one normal Rh D-positive individual and 2 DEL samples, carrying RHD1227A allele, were sequenced and aligned. Thirty-three and 27 nucleotide variants were totally observed in intron 7 and intron 9, respectively (EMBL/GenBank/DDBJ EU372940 approximately 2). Among them, 8 variants in intron 7 and 7 in intron 9 were observed commonly in all 3 samples, whereas 2 variants in intron 7 and one in intron 9 were only found in 2 DEL samples, but not in the normal D-positive. The variants observed in intron 7 in DEL cannot explain enough for that DEL mRNA has one segment of 170 base pairs sequence from intron 7. But the nucleotides AG-GT at both sides of the segment may be related to this molecular even as AG-GT may cut intron 7 with its normal splicing site (GT-AG) into two "new introns" although the mechanisms are complicated in fact. We also have not found any suspicious splicing-affecting variants in intron 9 of DEL allele. However, this may make out further that the reason of whole exon 9 spliced out in DEL mRNAs may be no more than the 1227A>G mutation in DEL allele.