Alport-like glomerular basement membrane changes with renal-coloboma syndrome

Abstract

Autosomal dominant mutations in paired box gene 2 (PAX2), on chromosome 10q24, are responsible for renal coloboma syndrome (RCS). The role of PAX2 in glomerular basement membrane (GBM) formation and maintenance remains unknown. We report a case of a 13-year-old Japanese girl who had both optic disk coloboma and renal insufficiency. Her father and sister also had both coloboma and renal dysfunction. Renal pathological findings revealed a basket-weave pattern of the GBM, which was compatible with Alport syndrome, but type IV collagen α5 staining was normal. The patient's findings of coloboma and renal dysfunction suggested that she had RCS, and genetic analysis revealed a PAX2 heterozygous mutation in exon 2 (c.76dup, p.Val26Glyfsx27) without any mutations of COL4A3, COL4A4, and COL4A5, which are responsible for autosomal and X-linked Alport syndrome. PAX2 mutations may result in abnormal GBM structure.