Tonal audiometry revealedhearing per ceptive deafness of 25 dB, which was more prominent in the left ear.Because the patterns of progressive sensorineural hearing loss and congenitalhereditary endothelial dystrophy have both been linked to the same gene,slc4a11, we tested our patient for mutations in this gene.The test was positive for a heterozygous slc4a11 gene fifthexon mutation on chromosome 20p13-p12, which causes a frameshift. This evidence concerns the gene SLC4A11 and hearing loss disorder.