[Analysis of the clinical audiological characteristics in 92 Chinese Alport syndrome cases].

OBJECTIVE: To analyze the clinical audiological characteristics in Chinese Alport syndrome, and investigate the relationship between the genotypes of Alport syndrome and hearing phenotype.

METHODS: The clinical hearing data of 92 cases diagnosed as Alport syndrome from 2008 August to 2013 August were reviewed and analyzed. All coding exons of COL4A3 and COL4A5 genes were PCR-amplified and sequenced from genomic DNA, or mRNA of COL4A5 gene was RT-PCR-amplified and sequenced from skin fibroblast in 17 cases.

RESULTS: Eighty-seven out of 92 cases were found with X-linked dominant inheritance (XLAS); 5 cases with autosomal recessive (ARAS); 44 cases had normal hearing, but 14 young cases had abnormal OAE; 48 cases (52.2%, 35 male, 13 female) had sensorineural hearing loss. A total of 44 cases with XLAS had hearing loss (49.4%), wherein the incidence of hearing impairment was 55.0% in male XLAS, and 37.0% in female XLAS. Mild and moderate hearing loss were found in XLAS. Audiometric curves including groove type (21 cases), descending type (13 cases), flat type (10 cases), high frequency drop type (3 cases) and ascending type (1 case) were found in AS. Sixteen mutations of COL4A3, COL4A5 gene were found in 17 cases with Alport syndrome, including severe mutation in 8 cases with moderate hearing impairment.

CONCLUSIONS: Mild and moderate hearing impairment, and groove type of audiometric curve are mainly found in Chinese Alport syndrome, which is different from Alport syndrome in western countries. OAE in the early diagnosis of hearing loss is important. Hearing phenotype is related certainly with genotype.