Audiologic findings in distal renal tubular acidosis

Distal renal tubular acidosis (dRTA) is a disease characterized by disruption of the excretion of H+ ions from the distal renal tubules. Different types and degrees of hearing loss can be seen in gene mutations that cause autosomal recessive form of dRTA. The aim of this study is to investigate the relationship between hearing loss and gene mutations in individuals with dRTA, to determine the audiological characteristics in these individuals and to emphasize the importance of audiological follow-up. For this purpose, 21 individuals with dRTA were included in the study and an audiological test battery including Ear Nose Throat examination, behavioral tests, immitansmetric assessment, otoacoustic emission measurements and auditory brainstem responses were applied. As a result of audiological evaluations, hearing loss was detected in all 7 individuals with ATP6V1B1 mutation, in 1 of 6 individuals with ATP6V0A4 mutation, in 1 individual with SLC4A2 mutation and in 4 of 6 individuals who could not reach genetic analysis results. Hearing was within normal limits in an individual with the WDR72 mutation. Pure tone averages were significantly higher in individuals with ATP6V1B1 mutation than individuals with ATP6V0A4 mutation. Types of hearing loss were sensorineural type in 9 individuals, mixed type in 3 individuals and conductive type in 1 individual. Age at the time of diagnosis of hearing loss was between 0 and 6 months in 5 individuals, between 6 months and 4 years in 6 individuals, and 4 years or more in 2 individuals. In addition, LVAS was detected in 6 of 8 patients with radiological imaging results. These results show that hearing loss seen in dRTA has great variability in different gene mutations in terms of onset age, type and degree. This demonstrates the importance of regular audiological follow-up in individuals with dRTA for timely diagnosis and effective management of hearing loss. These results also indicate that the possibility of Large Vestibular Aquaduct Syndrome (LVAS) should be taken into consideration in the follow-up process in individuals with dRTA and it would be beneficial to evaluate individuals in terms of LVAS.