[Genetic and clinical analysis of a pedigree affected with X-linked dominant Alport syndrome due to a novel variant of COL4A5 gene].

OBJECTIVE To explore the genetic basis for a Chinese pedigree affected with X-linked hereditary Alport syndrome. METHODS Next generation sequencing was carried out for the pedigree. Candidate variant was validated by Sanger sequencing. Pathological changes of renal basement membrane and expression of COL4A5 protein were analyzed by renal biopsy and immunofluorescence assay, respectively. RESULTS All patients from the pedigree manifested progressive renal damage, gross hematuria, proteinuria and nephrotic syndrome. Renal biopsy of the proband revealed thickening of the basement membrane. No expression of the COL4A5 gene was detected by immunofluorescence. High-throughput sequencing and Sanger sequencing indicated that the proband has carried a c.3706delC (p.1236Pfs*69) variant in exon 41 of the COL4A5 gene. The same variant was also found in his mother and two brothers whom were similarly affected. CONCLUSION The novel c.3706delC (p.1236Pfs*69) variant of the COL4A5 gene probably underlay the pathogenesis of X-linked hereditary Alport syndrome in this pedigree. Above findings have enriched the spectrum of COL4A5 gene variants and provided a basis for the diagnosis and genetic counseling for the pedigree.