COL4A4 and X-linked Alport syndrome: In the LOVD database, the age at kidney failure was not different for AR and for X-linked Alport syndrome (24.4 ± 7.8 years, n = 237, p = 0.39), and in the case of AR disease, was not different for COL4A3 (23.2 ± 9.3, n = 35, p = 0.45) or COL4A4 (25.4 ± 10.3, n = 26, p = 0.55) variants (7).