OBJECTIVETo analyze the clinical and genetic features of X-linked Alport syndrome (XLAS) in men positive for the collagen α5(Ⅳ) chain in epidermal basement membrane.

METHODThis was a retrospective study. Totally 725 families were diagnosed as Alport syndrome in Department of Pediatrics of Peking University First Hospital during January 1998 to December 2014, among them 450 patients were males with XLAS. Patients who met both of the following two criteria were included in this study. (1)Patients underwent α5(Ⅳ) chain staining in the epidermal basement membrane. (2)Mutations in COL4A5 gene were detected.Mann-Whitney test and χ(2) test were used.

RESULTTotally 140 males with XLAS were included in this study, 18 cases were α5 (Ⅳ)-positive and 122 cases were α5 (Ⅳ)-negative. The two groups of patients were compared, the median age at analysis was 11.0 vs. 7.2 years (Z = -1.839, P = 0.066), the 24-hour urine protein was 1.50 vs. 0.57 g/d (Z = -1.212, P = 0.226), the rate of hearing loss was 28% vs. 53% (χ(2) = 3.619, P = 0.067), the number of patients progressed to end stage renal disease (ESRD) was 4 vs. 12 (χ(2) =2.377, P = 0.128), the median age of ESRD was 31.0 vs. 16.6 years (Z = -2.554, P = 0.011), the rate of missense mutations in COL4A5 gene was 67% vs. 52% (χ(2) = 1.424, P = 0.313).

CONCLUSIONCompared the two groups of patients with positive and negative staining for the collagen Ⅳ α5 chain in epidermal basement membrane, there was no significant difference in the proteinuria level, the rate of hearing loss and genotype of COL4A5 gene. But the patients with positive staining progressed to ESRD significantly later than the patients with negative staining.