A Rapid Point of Care Test for APOL1 Renal Risk Alleles

总结/摘要 非裔美国人不成比例地受到慢性和终末期肾病（ESRD）的影响;而35%的 透析患者是非洲裔美国人，只有13.2%的美国人口是非洲裔美国人。一个因素 导致这种差异的是载脂蛋白L1（APOL 1）的遗传变异。APOL1是一种血浆蛋白， 一种未知的细胞功能，可以防止大多数非洲人引起的人类昏睡病。 布氏锥虫Rhodesiense或T. B gambiense。在人类中，有三种主要的 APOL1的等位基因变体：G0（野生型）、G1和G2。G1和G2 APOL 1等位基因（即肾脏风险等位基因） 赋予抵抗昏睡病，而G0等位基因使寄生虫生存和感染。为此 因此，G1和G2等位基因在具有非洲血统的个体中普遍存在。虽然有利于抵抗 昏睡病，G1和G2变体也与ESRD的风险大大增加有关， 从具有两个风险等位基因的供体移植的肾中减少同种异体移植物寿命。仅表达一个拷贝 G0变异体在肾脏供体中的表达增加了同种异体移植物的寿命，减少了再次移植，并消除了 与G1/G2风险变异相关的ESRD风险增加，无论受体APOL1状态如何。它遵循 基于肾脏供体中APOL1变异表达的准确风险评估对于肾脏供体至关重要， 安全性、捐赠者知情同意，以及根据预计的术后情况将肾脏正确分配给接受者。 移植存活率此外，用APOL 1状态代替非裔美国人种族作为风险因素， 预计肾脏捐献者风险指数将消除对非洲血统捐献者的不必要惩罚 没有两个风险等位基因，从而增加了批准移植的肾脏数量。然而，目前的测试 对于APOL1状态，没有FDA批准，需要基因测序或质谱分析，技术上 在移植前风险评估可用的1小时时间范围内， 死亡捐献者（> 70%的肾脏捐献者）。APOL1变异体的结构差异，与 与锥虫蛋白质的差异结合，使该系统成为测定开发的合适靶。 Affinergy计划开发一种简单，快速的床旁检测，用于确定APOL1 G0状态， 为医疗保健决策提供信息，改善活体和死者移植前的风险分层 捐赠肾脏，支持活体捐赠者做出知情的捐赠决定，并可能增加 可供捐赠的肾脏数量。在第二阶段结束时，我们预计将有一个快速测试准备就绪 进行验证和确认研究

SUMMARY/ABSTRACT African Americans are disproportionately affected by chronic and end stage renal disease (ESRD); while 35% of patients on dialysis are African American, only 13.2% of the U.S. population is African American. One factor contributing to this disparity is genetic variation in apolipoprotein L1 (APOL1). APOL1 is a plasma protein of unknown cellular function that is protective against human sleeping sickness caused by most African trypanosomes but not Trypanosoma brucei rhodesiense or T.b gambiense. In humans, there are three main allelic variants of APOL1: G0 (wild-type), G1, and G2. The G1 and G2 APOL1 alleles (i.e. renal risk alleles) impart resistance to sleeping sickness, while the G0 allele enables parasite survival and infection. For this reason, the G1 and G2 alleles are prevalent in individuals with African ancestry. While beneficial for resisting sleeping sickness, the G1 and G2 variants are also associated with a greatly increased risk for ESRD and reduced allograft longevity in kidneys transplanted from donors with two risk alleles. Expression of just one copy of the G0 variant in kidney donors improves allograft longevity, reduces re-transplantations and eliminates the increased risk for ESRD associated with the G1/G2 risk variants, regardless of recipient APOL1 status. It follows that accurate risk assessment based on APOL1 variant expression in kidney donors is critical for kidney donor safety, donor informed consent, and the proper allocation of kidneys to recipients based on projected post- transplant survival. Additionally, substituting APOL1 status instead of African American race as a risk factor on the Kidney Donor Risk Index is predicted to remove unnecessary penalties applied to donors of African ancestry without two risk alleles, thus increasing the number of kidneys approved for transplant. However, current tests for APOL1 status are not FDA-cleared and require gene sequencing or mass-spectrometry which are technically challenging and infeasible during the 1-hour timeframe available for the pre-transplant risk evaluation of deceased donors (>70% of all kidney donors). Structural differences in the APOL1 variants, in combination with differential binding to a trypanosome protein, make this system a suitable target for assay development. Affinergy plans to develop a simple, rapid point of care test for the determination of APOL1 G0 status to inform healthcare decisions, improve risk stratification prior to transplantation of living and deceased donor kidneys, support informed donation decisions among living donors and potentially increase the number of available kidneys for donation. At the conclusion of Phase II, we expect to have a rapid test ready for verification and validation studies ahead of FDA clearance.