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.
Matejas et al. (2006) presented a non-consanguineous Emirati family of Baluchi origin with seven offspring affected by various symptoms belonging to Pierson syndrome. These symptoms included childhood-onset nephrotic syndrome progressing to end-stage renal failure and ocular abnormalities including cataracts, anterior chamber and iris abnormalities, and progressive blindness due to retinal detachment. The causative mutations were found to affect the LAMB2 gene as patients were heterozygous for two novel mutations; p.Q1728X, and p.triangle upV79. This combination between a complete loss-of-function (LOF) allele with a partial LOF one may explain the milder form of Pierson syndrome affecting this family.