Molecular Basis of Dominantly Inherited Kidd-null Phenotype

描述（由申请人提供）：Kidd抗原系统（包括Jka和Jkb抗原）在输血医学中非常重要，因为暴露个体的所有免疫接种均可引起严重的急性和迟发性溶血性输血反应以及新生儿溶血性疾病。由于SLC 14 A1基因中的双等位基因突变，Kidd-null血型最常作为隐性遗传性状遗传，该基因编码具有Jka和Jkb抗原的蛋白质。虽然在1965年首次描述了显性遗传[In（Jk）]的相同Kidd无效表型的原因，但尚未确定。我们建议确定以前从未描述过的Kidd无效表型的分子原因。由SLC 14 A1基因编码并展示Kidd抗原的蛋白质是尿素转运蛋白UT-B1。Kidd-null表型不仅与输血风险相关，而且与由于肾脏中尿素转运蛋白表达减少而导致的浓缩尿液能力异常相关。通过与西班牙的实验室合作，克劳斯实验室获得了有史以来最广泛的In（Jk）人群。迄今为止，我们已经使用分子方法将受影响的基因座定位到19q13.11-13.2的5 Mbp区域，LOD评分为9.6。使用深度测序，我们已经确定了ZNF 850基因中的潜在有害突变，该突变缺失84 bp，导致整个zing finger结构域的丢失。相同的del 84 ZNF 850突变存在于所有受影响的个体中，并且在所有测试的对照中不存在（n>2000）。在本项目中，我们将测试del 84 ZNF 850是否负责抑制红系分化的原代人细胞上的Kidd抗原表达，如果不是，我们将进一步分析5 Mbp的感兴趣区域以鉴定导致这种表型的遗传异常。我们将确定Kidd抗原表达在In（Jk）细胞中被阻断的机制，并阐明19号染色体上的遗传异常导致In（Jk）表型的分子机制。所获得的数据将与输血医学、肾生理学相关，并且还可能阐明蛋白质特异性细胞内运输的新的特异性机制。

DESCRIPTION (provided by applicant): The Kidd antigen system, which includes the Jka and Jkb antigens, is of great importance in transfusion medicine because all immunization of exposed individuals can cause severe acute and delayed hemolytic transfusion reactions as well as hemolytic disease of the newborn. The Kidd---null blood group is most often inherited as a recessive genetic trait due to bi-allelic mutations in the SLC14A1 gene, which encodes the protein that has the Jka and Jkb antigens. The cause of the identical Kidd-null phenotype with dominant inheritance [In(Jk)] has not yet been defined, though it was first described in 1965. We are proposing to identify the never before described molecular cause of the Kidd-null phenotype. The protein encoded by the SLC14A1 gene, and displaying the Kidd antigens, is the urea transporter UT-B1. The Kidd---null phenotype is associated not only with transfusion risk, but also with abnormalities in the ability to concentrate urine due to decrease expression of this urea transporter in the kidney. In collaboration with laboratories in Spain, the Krause laboratory has access to the most extensive population with In(Jk) ever described. To date, we have used molecular approaches to map the affected locus to a 5 Mbp region in 19q13.11-13.2 with an LOD score of 9.6. Using deep sequencing, we have identified a potential deleterious mutation in the ZNF850 gene, which deletes 84 bp resulting in loss of an entire zing finger domain. The identical del84 ZNF850 mutation is present in all affected individuals, and is absent from all controls tested (n>2000). In the present project, we will test whether del84 ZNF850 is responsible for inhibition of Kidd antigen expression on primary human cells differentiated down the erythroid lineage, and if not, we will further analyze the 5Mbp region of interest to identify he genetic abnormality that causes this phenotype. We will determine the mechanism by which Kidd antigen expression is blocked in In(Jk) cells, and we will elucidate the molecular mechanism by which the genetic abnormalities on chromosome 19 cause the In(Jk) phenotype. The data obtained will have relevance to transfusion medicine, renal physiology, and will likely also elucidate novel specific mechanisms for protein-specific intracellular trafficking.