Homozygous and compound heterozygous mutations in the ATP6V1B1 gene in patients with renal tubular acidosis and sensorineural hearing loss
Article first published online: 10 MAY 2012
© 2012 John Wiley & Sons A/S
Volume 83, Issue 3, pages 274–278, March 2013
How to Cite
Mohebbi, N., Vargas-Poussou, R., Hegemann, S., Schuknecht, B., Kistler, A., Wüthrich, R. and Wagner, C. (2013), Homozygous and compound heterozygous mutations in the ATP6V1B1 gene in patients with renal tubular acidosis and sensorineural hearing loss. Clinical Genetics, 83: 274–278. doi: 10.1111/j.1399-0004.2012.01891.x
- Issue published online: 18 FEB 2013
- Article first published online: 10 MAY 2012
- Accepted manuscript online: 17 APR 2012 10:50AM EST
- Received 7 February 2012, revised and accepted for publication 11 April 2012
- distal renal tubular acidosis;
- enlarged vestibular aqueduct;
- proton pump
Mohebbi N, Vargas-Poussou R, Hegemann SCA, Schuknecht B, Kistler AD, Wüthrich RP, Wagner CA. Homozygous and compound heterozygous mutations in the ATP6V1B1 gene in patients with renal tubular acidosis and sensorineural hearing loss.
Distal renal tubular acidosis (dRTA) is characterized by the inability to excrete acid in the renal collecting ducts resulting in inappropriately alkaline urine and hyperchloremic (normal anion gap) metabolic acidosis in the context of a normal (or near-normal) glomerular filtration rate. Inborn dRTA can be due to autosomal dominant or recessive gene defects. Clinical symptoms vary from mild acidosis, incidental detection of kidney stones or renal tract calcification to severe findings such as failure to thrive, severe metabolic acidosis, and nephrocalcinosis. The majority of patients with recessive dRTA present with sensorineural hearing loss (SNHL). Few cases with abnormal widening of the vestibular aqueduct have been described with dRTA. Mutations in three different genes have been identified, namely SLC4A1, ATP6V1B1, and ATP6V0A4. Patients with mutations in the ATP6V1B1 proton pump subunit develop dRTA and in most of the cases sensorineural hearing loss early in childhood. We present two patients from two different and non-consanguineous families with dRTA and SNHL. Direct sequencing of the ATP6V1B1 gene revealed that one patient harbors two homozygous mutations and the other one is a compound heterozygous. To our knowledge, this is the first case in the literature describing homozygosity in the same dRTA gene on both alleles.