The healthy mother (62 years of age), one healthy sister (33 years of age), and the healthy son of ATS-F521-II-2 (16 years of age) also carry the variant in COL4A3. One additional sister of ATS-F521-II-2 also suffers from hearing impairment but has no renal phenotype. The gene discussed is COL4A3; the disease is Hearing impairment.