Liu Hsiang-Chun, Eng Hock-Liew, Yang Yu-Fen, Wang Ya-Hui, Lin Kuan-Tsou, Wu Hua-Lin, Lin Tsun-Mei
Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan.
Biochim Biophys Acta. 2010 Jun;1800(6):565-73. doi: 10.1016/j.bbagen.2010.02.006. Epub 2010 Feb 25.
The Rh blood D group provides a clinically important model of aberrant splicing with skipped exons. Approximately 30% of serologically D-negative Chinese individuals have an intact RHD gene (DEL phenotype) and induce allo-immunization in transfusions. The RHD1227GNA polymorphism occurs in >95% DEL phenotype of Asian descent. The effects of RHD 1227A and a novel allele on exon 9 splicing were examined.
Amplified DEL RNA products revealed that 3 transcripts involved skipping of exons 8-9, exon 9, or exon 9 with an inserted 170-bp cryptic exon located between exons 7 and 8. A novel, single nucleotide polymorphism was identified in the 7th intron, (IVS7) 923C>T, and present in all DEL patients. The odds ratio of RHD1227G>A allele with DEL phenotype was 2711. Splicing analysis of transcripts from minigenes containing the 1227GNA allele, but not the (IVS7) 923C>T allele, demonstrated aberrant exon 9 skipping.
A combined haplotype of 1227G>A and IVS7 923C>T alleles was apparent in >95% DEL Chinese individuals. RHD1227A mutation significantly increased aberrant mRNA splicing, producing a hybrid RHD mRNA lacking exon 9. These results provide a molecular basis of the DEL phenotype in the Chinese population.
Rh血型D组提供了一个具有外显子跳跃的异常剪接的重要临床模型。约30%血清学D阴性的中国个体具有完整的RHD基因（DEL表型），并在输血中诱导同种免疫。RHD1227GNA多态性出现在>95%的亚洲血统DEL表型中。研究了RHD 1227A和一个新等位基因对外显子9剪接的影响。
扩增的DEL RNA产物显示，3种转录本涉及外显子8-9、外显子9或外显子9的跳跃，且在外显子7和8之间插入了一个170 bp的隐蔽外显子。在第7内含子中鉴定出一个新的单核苷酸多态性，即（IVS7）923C>T，且存在于所有DEL患者中。RHD1227G>A等位基因与DEL表型的优势比为2711。对含有1227GNA等位基因而非（IVS7）923C>T等位基因的微型基因转录本进行剪接分析，显示外显子9异常跳跃。
1227G>A和IVS7 923C>T等位基因的联合单倍型在>95%的中国DEL个体中明显。RHD1227A突变显著增加异常mRNA剪接，产生缺乏外显子9的杂合RHD mRNA。这些结果为中国人群中DEL表型提供了分子基础。
