Do mutations of the Pendred syndrome gene, SLC26A4, confer resistance to asthma and hypertension?

Background and aims: Mutations of SLC26A4 cause Pendred syndrome, an autosomal recessive disorder comprising goitre and deafness with enlarged vestibular aqueducts (EVA). Recent studies in mouse models implicate Slc26a4 in the pathogenesis of asthma and hypertension. We hypothesise that asthma and hypertension are less prevalent among humans with SLC26A4 mutations. Methods: We reviewed medical histories and SLC26A4 genotypes for 80 individuals with EVA and 130 of their unaffected family members enrolled in a study of EVA. We used Fisher's exact test to compare the prevalence of asthma and hypertension among groups of subjects with zero, one, or two mutant alleles of SLC26A4. Results: Although none of the 21 subjects with two mutant alleles of SLC26A4 had asthma or hypertension, there were no statistically significant differences in the prevalence of asthma or hypertension among subjects with zero, one, or two mutant alleles. Conclusion: There might be a protective effect of SLC26A4 mutations for asthma and hypertension but our study is statistically underpowered to detect this effect. Study sizes of at least 1125 and 504 individuals will be needed for 80% power to detect an effect at alpha=0.05 for asthma and hypertension, respectively. Our hypothesis merits a larger study since it has implications for potential strategies to treat hearing loss by manipulating SLC26A4 expression or function.