A child with phenylketonuria and focal segmental glomerulosclerosis, the bright side of proteinuria

Phenylketonuria (PKU) is the most common inborn error of amino acid metabolism. Phenylalanine hydroxylase is the underlying deficient enzyme. If left untreated, growth failure, microcephaly, global developmental delay, seizures and severe intellectual impairment would characterize the clinical picture of PKU. On the other side of protein homeostasis lies nephrotic syndrome. It is a well-known quantitative defect due to significant proteinuria. Focal segmental glomerulosclerosis (FSGS) is a special congenital variant affecting children and adults. Hereby, we describe a three- year old male child who presented with generalized edema and global developmental delay. Investigations revealed PKU along with FSGS. We assume that congenital nephrosis ameliorated the picture of PKU, and had a salutary effect on the growth and development. Such coexistence between PKU and FSGS hasn't been described before.