Renal complications in 6p duplication syndrome: Microarray-based investigation of the candidate gene(s) for the development of congenital anomalies of the kidney and urinary tract (CAKUT) and focal segmental glomerular sclerosis (FSGS)

6p duplication syndrome is a rare chromosomal disorder that frequently manifests renal complications, including proteinuria, hypoplastic kidney, and hydronephrosis. We report a girl with the syndrome, manifesting left hydronephrosis, proteinuria/hematuria, and focal segmental glomerular sclerosis (FSGS) resulting in chronic end-stage renal failure, successfully treated with renal transplantation. Microarray comparative genomic hybridization showed the derivative chromosome 6 to have a 6.4-Mb duplication at 6p25.3-p25.1 with 32 protein-coding genes and a 220-Kb deletion at 6p25.3 with two genes of no possible relation to the renal pathology. Review of the literature shows that variation of renal complications in the syndrome is compatible with congenital anomalies of the kidney and urinary tract (CAKUT). FSGS, observed in another patient with 6p duplication syndrome, could be a non-coincidental complication. FOXC1, located within the 6.4-Mb duplicated region at 6p25.3-p25.2, could be a candidate gene for CAKUT, but its single gene duplication effect would not be sufficient. FSGS would be a primary defect associated with duplicated gene(s) albeit no candidate could be proposed, or might occur in association with CAKUT.