Pierson syndrome is an autosomal recessive disorder, which combines congenital nephrotic syndrome presenting as diffuse mesangial sclerosis, with a complex ocular maldevelopment, the most striking feature of which is extreme and fixed narrowing of the pupils (microcoria). Patients with Pierson syndrome may also suffer severe neurodevelopmental deficits including congenital muscular weakness/myasthenia and developmental retardation.
The association of early-onset nephrotic syndrome and microcoria should direct diagnosis towards Pierson syndrome. Similarly, detecting hyperechogenic kidneys and oligohydramnio prenatally points out to this syndrome. Molecular antenatal diagnosis can be offered to families when their causative mutation is known. Most patients die due the disease progressing to renal failure within the first days or months of life. Patients who survive infancy due to renal replacement therapy are blind and may develop severe neurological deficits.