Mutation of SLC9A1, encoding the major Na⁺/H⁺ exchanger, causes ataxia-deafness Lichtenstein-Knorr syndrome.

Claire Guissart, Xiuju Li, Bruno Leheup, Nathalie Drouot, Bettina Montaut-Verient, Emmanuel Raffo, Philippe Jonveaux, Anne-Françoise Roux, Mireille Claustres, Larry Fliegel, Michel Koenig

Human molecular genetics 2015 Jan 15

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Lichtenstein-Knorr syndrome is an autosomal recessive condition that associates sensorineural hearing loss and cerebellar ataxia. Here, we report the first identification of a gene involved in Lichtenstein-Knorr syndrome. By using a combination of homozygosity mapping and whole-exome sequencing, we identified the homozygous p.Gly305Arg missense mutation in SLC9A1 that segregates with the disease in a large consanguineous family. Mutant glycine 305 is a highly conserved amino acid present in the eighth transmembrane segment of all metazoan orthologues of NHE1, the Na(+)/H(+) exchanger 1, encoded by SLC9A1. We demonstrate that the p.Gly305Arg mutation causes the near complete de-glycosylation, mis-targeting and loss of proton pumping activity of NHE1. The comparison of our family with the phenotypes of spontaneous and knockout Slc9a1 murine models demonstrates that the association between ataxia and hearing loss is caused by complete or near complete loss of function of NHE1 and altered regulation of pHi in the central nervous system. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Citation

Claire Guissart, Xiuju Li, Bruno Leheup, Nathalie Drouot, Bettina Montaut-Verient, Emmanuel Raffo, Philippe Jonveaux, Anne-Françoise Roux, Mireille Claustres, Larry Fliegel, Michel Koenig. Mutation of SLC9A1, encoding the major Na⁺/H⁺ exchanger, causes ataxia-deafness Lichtenstein-Knorr syndrome. Human molecular genetics. 2015 Jan 15;24(2):463-70