Spectrum of clinical features and type IV collagen alpha-chain distribution in Chinese patients with Alport syndrome.

BACKGROUND: Alport syndrome (AS) is a clinically and genetically heterogeneous nephropathy. The goal of the present study is to delineate clinical characteristics and the distribution of type IV collagen chains in Chinese AS patients and to identify any alpha(IV)-chain expression and clinical phenotype correlation. METHODS: A total of 126 biopsy-proven patients meeting immunofluorescence criteria for the diagnosis of AS were investigated retrospectively. RESULTS: Microscope haematuria associated with proteinuria was observed as the initial symptom in 77.8% of the patients; 59.8% showed hearing impairment and 22.9% had ocular abnormalities. Renal biopsies from 118 patients revealed mesangial proliferative glomerulonephritis (61.9%) and focal and segmental sclerosis glomerulonephritis (37.3%). Ten different distribution patterns for the type IV collagen alpha-chains were found in the kidney; six of these are presented here for the first time. Based on renal immunofluorescence findings, 113 patients (89.7%) were classified as X-linked dominant inherited AS (XLAS) and 13 (10.3%) as autosomal recessive AS (ARAS). The XLAS group was divided into typical and non-typical subgroups according to the expression patterns for the alpha3(IV)-chain. Clinical phenotypes were more severe in XLAS patients than in ARAS patients and the prognosis was poorer in typical XLAS patients than non-typical XLAS patients. CONCLUSION: In China, the incidence of XLAS is 89.7% and 10.3% for ARAS. Chinese patients with AS have various distribution patterns of type IV collagen alpha-chains. The distribution pattern of type IV collagen alpha-chains in the kidney may correspond to the severity of the clinical phenotype.