A Rapid Point of Care Test for APOL1 Renal Risk Alleles

摘要/摘要 非洲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 接受透析的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 造成这种差异的原因是载脂蛋白L1(APOL1)的遗传变异。载脂蛋白1是一种血浆蛋白 未知的细胞功能对大多数非洲人引起的人类昏睡病具有保护作用 而不是布氏锥虫或冈比亚锥虫。在人类中，有三个主要的 APOL1的等位基因变体：G0(野生型)、G1和G2。G1和G2载脂蛋白1等位基因(即肾脏风险等位基因) 赋予对昏睡病的抵抗力，而G0等位基因则使寄生虫存活和感染。为了这个 因此，G1和G2等位基因在非洲血统的个体中很普遍。虽然有益于抵抗 昏睡病，G1和G2变异也与ESRD和ESRD的风险大大增加有关 具有两个风险等位基因的供者移植的肾脏移植的同种异体移植寿命缩短。只有一个副本的表达 在肾捐赠者中发现G0变异可延长移植肾的寿命，减少再次移植，并消除 与G1/G2风险变异相关的ESRD风险增加，与接受者APOL1状态无关。它遵循的是 基于APOL1变异表达的准确风险评估对肾捐献者至关重要 安全性，捐赠者知情同意，以及根据预计的移植后肾脏向受者适当分配肾脏 移植存活率。此外，将APOL1状态取代非裔美国人种族作为风险因素 肾脏捐赠者风险指数预计将取消对非洲血统捐赠者的不必要惩罚 没有两个风险等位基因，从而增加了获准移植的肾脏数量。然而，目前的测试 对于APOL1状态，没有通过FDA的批准，需要基因测序或质谱分析，从技术上讲 在可用于移植前风险评估的1小时时间内具有挑战性和不可行 已故捐赠者(占所有肾脏捐赠者的70%)。APOL1变异体的结构差异，与 与锥虫蛋白的不同结合，使该系统成为适合分析开发的目标。 AffinEnergy计划开发一种简单、快速的护理点测试，用于确定APOL1 G0状态 告知医疗决策，改善活体和死者移植前的风险分层 捐献肾脏，支持在世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，我们希望有一个快速测试准备就绪 用于FDA批准之前的验证和验证研究。

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.