• A Founder Mutation in EHD1 Presents with Tubular Proteinuria and Deafness.

A Founder Mutation in EHD1 Presents with Tubular Proteinuria and Deafness.

Journal of the American Society of Nephrology : JASN (2022-02-13)
Naomi Issler, Sara Afonso, Irith Weissman, Katrin Jordan, Alberto Cebrian-Serrano, Katrin Meindl, Eileen Dahlke, Konstantin Tziridis, Guanhua Yan, José M Robles-López, Lydia Tabernero, Vaksha Patel, Anne Kesselheim, Enriko D Klootwijk, Horia C Stanescu, Simona Dumitriu, Daniela Iancu, Mehmet Tekman, Monika Mozere, Graciana Jaureguiberry, Priya Outtandy, Claire Russell, Anna-Lena Forst, Christina Sterner, Elena-Sofia Heinl, Helga Othmen, Ines Tegtmeier, Markus Reichold, Ina Maria Schiessl, Katharina Limm, Peter Oefner, Ralph Witzgall, Lifei Fu, Franziska Theilig, Achim Schilling, Efrat Shuster Biton, Limor Kalfon, Ayalla Fedida, Elite Arnon-Sheleg, Ofer Ben Izhak, Daniella Magen, Yair Anikster, Holger Schulze, Christine Ziegler, Martin Lowe, Benjamin Davies, Detlef Böckenhauer, Robert Kleta, Tzipora C Falik Zaccai, Richard Warth

The endocytic reabsorption of proteins in the proximal tubule requires a complex machinery and defects can lead to tubular proteinuria. The precise mechanisms of endocytosis and processing of receptors and cargo are incompletely understood. EHD1 belongs to a family of proteins presumably involved in the scission of intracellular vesicles and in ciliogenesis. However, the relevance of EHD1 in human tissues, in particular in the kidney, was unknown. Genetic techniques were used in patients with tubular proteinuria and deafness to identify the disease-causing gene. Diagnostic and functional studies were performed in patients and disease models to investigate the pathophysiology. We identified six individuals (5-33 years) with proteinuria and a high-frequency hearing deficit associated with the homozygous missense variant c.1192C>T (p.R398W) in EHD1. Proteinuria (0.7-2.1 g/d) consisted predominantly of low molecular weight proteins, reflecting impaired renal proximal tubular endocytosis of filtered proteins. Ehd1 knockout and Ehd1R398W/R398W knockin mice also showed a high-frequency hearing deficit and impaired receptor-mediated endocytosis in proximal tubules, and a zebrafish model showed impaired ability to reabsorb low molecular weight dextran. Interestingly, ciliogenesis appeared unaffected in patients and mouse models. In silico structural analysis predicted a destabilizing effect of the R398W variant and possible inference with nucleotide binding leading to impaired EHD1 oligomerization and membrane remodeling ability. A homozygous missense variant of EHD1 causes a previously unrecognized autosomal recessive disorder characterized by sensorineural deafness and tubular proteinuria. Recessive EHD1 variants should be considered in individuals with hearing impairment, especially if tubular proteinuria is noted.

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β₂-Microglobulin, Human, Recombinant, E. coli