Department of General Pediatrics, University Children's Hospital Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany.
Pediatr Nephrol. 2024 Dec;39(12):3471-3483. doi: 10.1007/s00467-024-06443-0. Epub 2024 Aug 5.
Nephronophthisis (NPH) comprises a heterogeneous group of inherited renal ciliopathies clinically characterized by progressive kidney failure. So far, definite diagnosis is based on molecular testing only. Here, we studied the feasibility of NPHP1 and NPHP4 immunostaining of nasal epithelial cells to secure and accelerate the diagnosis of NPH.
Samples of 86 individuals with genetically determined renal ciliopathies were analyzed for NPHP1 localization using immunofluorescence microscopy (IF). A sub-cohort of 35 individuals was also analyzed for NPHP4 localization. Western blotting was performed to confirm IF results.
NPHP1 and NPHP4 were both absent in all individuals with disease-causing NPHP1 variants including one with a homozygous missense variant (c.1027G > A; p.Gly343Arg) formerly classified as a "variant of unknown significance." In individuals with an NPHP4 genotype, we observed a complete absence of NPHP4 while NPHP1 was severely reduced. IF results were confirmed by immunoblotting. Variants in other genes related to renal ciliopathies did not show any impact on NPHP1/NPHP4 expression. Aberrant immunostaining in two genetically unsolved individuals gave rise for a further genetic workup resulting in a genetic diagnosis for both with disease-causing variants in NPHP1 and NPHP4, respectively.
IF of patient-derived respiratory epithelial cells may help to secure and accelerate the diagnosis of nephronophthisis-both by verifying inconclusive genetic results and by stratifying genetic diagnostic approaches. Furthermore, we provide in vivo evidence for the interaction of NPHP1 and NPHP4 in a functional module.
肾髓质囊性肾病（Nephronophthisis，NPH）由一组遗传性肾纤毛病组成，临床上以进行性肾功能衰竭为特征。到目前为止，明确诊断仅基于分子检测。在这里，我们研究了对鼻上皮细胞进行 NPHP1 和 NPHP4 免疫染色以确保和加速 NPH 诊断的可行性。
分析了 86 名遗传性肾纤毛病患者的基因样本，使用免疫荧光显微镜（IF）分析 NPHP1 的定位。对 35 名个体的亚组也进行了 NPHP4 定位分析。进行 Western blot 以确认 IF 结果。
所有具有致病性 NPHP1 变异的个体均缺乏 NPHP1 和 NPHP4，包括一名携带纯合错义变异（c.1027G > A；p.Gly343Arg）的个体，该变异以前被归类为“意义不明的变异”。在具有 NPHP4 基因型的个体中，我们观察到 NPHP4 完全缺失，而 NPHP1 则严重减少。IF 结果通过免疫印迹得到证实。与肾纤毛病相关的其他基因的变异对 NPHP1/NPHP4 的表达没有任何影响。在两个遗传上未解决的个体中异常免疫染色导致进一步的遗传研究，导致这两个个体分别具有致病性 NPHP1 和 NPHP4 变异的遗传诊断。
患者来源的呼吸上皮细胞的 IF 可能有助于确保和加速肾髓质囊性肾病的诊断-既可以通过验证不确定的遗传结果，也可以通过分层遗传诊断方法。此外，我们提供了 NPHP1 和 NPHP4 在功能模块中相互作用的体内证据。
