BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.
BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.
Authors: William C Skarnes; Barry Rosen; Anthony P West; Manousos Koutsourakis; Wendy Bushell; Vivek Iyer; Alejandro O Mujica; Mark Thomas; Jennifer Harrow; Tony Cox; David Jackson; Jessica Severin; Patrick Biggs; Jun Fu; Michael Nefedov; Pieter J de Jong; A Francis Stewart; Allan Bradley Journal: Nature Date: 2011-06-15 Impact factor: 49.962
Authors: L Mintz; E Galperin; M Pasmanik-Chor; S Tulzinsky; Y Bromberg; C A Kozak; A Joyner; A Fein; M Horowitz Journal: Genomics Date: 1999-07-01 Impact factor: 5.736
Authors: Avery D Posey; Kaitlin E Swanson; Manuel G Alvarez; Swathi Krishnan; Judy U Earley; Hamid Band; Peter Pytel; Elizabeth M McNally; Alexis R Demonbreun Journal: Dev Biol Date: 2014-01-17 Impact factor: 3.582
Authors: Sibel Kantarci; Lihadh Al-Gazali; R Sean Hill; Dian Donnai; Graeme C M Black; Eric Bieth; Nicolas Chassaing; Didier Lacombe; Koen Devriendt; Ahmad Teebi; Maria Loscertales; Caroline Robson; Tianming Liu; David T MacLaughlin; Kristin M Noonan; Meaghan K Russell; Christopher A Walsh; Patricia K Donahoe; Barbara R Pober Journal: Nat Genet Date: 2007-07-15 Impact factor: 38.330