Abstract：
Complexities of D within the Rh blood group system have long been recognized, initially using basic serologic testing and, more recently, using advanced and sensitive typing reagents. Discrepancies may arise when an individual carries a D antigen showing altered D antigen expression. These D variants are clinically important, since they may lead to production of anti-D in the carrier and induce alloimmunization in D- recipients, making their correct identification imperative. For clinical purposes, D variants can be classified into three groups: weak D, partial D, and DEL. The problem surrounding proper characterization of D variants exists because routine serologic tests are sometimes inadequate to detect D variants or resolve discrepant or ambiguous D typing results. Today, molecular analysis has revealed more than 300 RH alleles and is a better method for investigating D variants. Global distribution of variants differs, as observed in European, African, and East Asian populations. Discovery of the novel RHD*01W.150 (weak D type 150) with a nucleotide change of c.327_487-4164dup is proof. This variant, the result of an insertion of a duplicated exon 3 between exons 2 and 4 in the same orientation, was detected in more than 50 percent of Indian D variant samples in a 2018 study. The outcome of studies worldwide has led to the recommendation to manage D variant individuals as D+ or D- according to RHD genotype. The policies and workup with respect to D variant testing in donors, recipients, and prenatal women differ among blood banks, depending on type of variants predominantly encountered. Thus, a general genotyping protocol cannot be followed globally, and an Indian-specific RHD genotyping assay (multiplex polymerase chain reaction) designed to detect D variants frequently found in the Indian population was developed to save time and resources. This assay is also helpful for detecting several partial and null alleles. Identification of D variants by serology and characterization by molecular testing need to go hand-in-hand for better and safer transfusion practices.
摘要：
Rh血型系统中D的复杂性早已被认识到，最初使用基本血清学检测，最近,使用先进和灵敏的分型试剂。当个体携带显示改变的D抗原表达的D抗原时,可能出现差异。这些D变异在临床上很重要,因为它们可能导致载体中产生抗D，并在D受体中诱导同种免疫，使他们的正确识别势在必行。为了临床目的，D变体可分为三组：弱D，局部D,DEL。由于常规血清学测试有时不足以检测D变体或解决不一致或模棱两可的D分型结果，因此存在围绕D变体正确表征的问题。今天,分子分析揭示了300多个RH等位基因，是研究D变体的更好方法。变体的全球分布不同，正如在欧洲观察到的那样，非洲,和东亚人口。发现具有c.327_487-4164dup核苷酸变化的新型RHD*01W.150（弱D型150）就是证据。这个变种,以相同方向在外显子2和外显子4之间插入重复外显子3的结果，在2018年的一项研究中，超过50%的印度D变异样本中检测到。全球研究的结果导致建议根据RHD基因型将D变异个体管理为D+或D-。关于捐助者D变体测试的政策和工作，收件人,和产前妇女不同的血库，取决于主要遇到的变异类型。因此，通用的基因分型方案不能在全球范围内遵循，并开发了一种印度特异性RHD基因分型测定（多重聚合酶链反应），旨在检测在印度人口中经常发现的D变体，以节省时间和资源。该测定还有助于检测几个部分和无效等位基因。通过血清学鉴定D变体和通过分子测试表征需要齐头并进，以实现更好和更安全的输血实践。
