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A rare syndrome characterised by the association of congenital nephrotic syndrome and ocular anomalies with microcoria.
ORPHA:2670Classification level: Disorder
Less than 30 cases have been described in the literature so far.
Pierson syndrome results in proteinuria with nephrotic syndrome and histological lesions marked by diffuse mesangial sclerosis. Ocular anomalies are present from birth and include microcoria (small pupils that are not responsive to light) associated with absence of the pupillary dilator muscle in the iris, ciliary muscle atrophy, and abnormal eye development with lens-shape, retinal and corneal anomalies. Marked muscle hypotonia, movement disorders and psychomotor delay have also been reported.
Mutations in the LAMB2 gene (3p21) encoding laminin beta 2 have been identified. Laminin beta 2 is expressed in the glomerular basement membrane at the neuromuscular junctions, as well as in the intraocular muscles, lens and retina.
Prenatal diagnosis may be suspected following ultrasound detection of hyperechogenic kidneys and oligohydramnios. Antenatal diagnosis may be offered to families in which the disease-causing mutation has already been identified.
The disease is transmitted as an autosomal recessive trait.
The prognosis is severe, with most patients progressing towards renal failure within the first days or months of life.