LAMB2 mutations cause Pierson syndrome (OMIM 609049), an autosomal recessive genetic disease typically characterized by congenital nephrotic syndrome (CNS) and early onset renal failure, as well as bilateral microcoria.
These findings demonstrate that the spectrum of LAMB2-associated disorders is broader than previously anticipated and includes congenital nephrotic syndrome without eye anomalies or with minor ocular changes different from those observed in Pierson syndrome.
Mutation of the LAMB2 gene is associated with Pierson syndrome, which is an autosomal recessive disorder characterized by congenital nephrotic syndrome and ocular abnormalities.
The majority of disease-causing LAMB2 mutations are truncating, consistent with the hypothesis that loss of laminin beta2 function is the molecular basis of Pierson syndrome.
Mutations in LAMB2 that impact the synthesis or function of laminin α5β2γ1 (LM-521) cause Pierson syndrome (congenital nephrotic syndrome with eye and neurological defects) and its less severe variants, including isolated congenital nephrotic syndrome.
The most common mutations are in 4 genes, 3 of which are podocyte genes: NPHS1 (Finnish nephropathy), NPHS2 (podocin-induced focal segmental glomerulosclerosis), WT1 (diffuse mesangial sclerosis), and LAMB2 (Pierson syndrome).
This observation, together with two recent reports on milder variants of Pierson syndrome, corroborates the concept that the clinical expression of Pierson syndrome is more variable than initially described, and that milder phenotypes may be related to hypomorphic LAMB2 alleles.
Genetic diseases affecting laminin and type IV collagen synthesis also are presented, with an emphasis on mutations to LAMB2 (Pierson syndrome) and COL4A3, COL4A4, and COL4A5 (Alport syndrome), and their experimental mouse models.
What is known • LAMB2 mutations are associated with Pierson syndrome • Pierson syndrome is associated with congenital nephrotic syndrome, microcoria and neurological deficits What is new • A novel mutation in the LAMB2 gene in two female siblings • Genotype and clinical phenotype description of a novel LAMB2 mutation.
The majority of disease-causing LAMB2 mutations are truncating, consistent with the hypothesis that loss of laminin beta2 function is the molecular basis of Pierson syndrome.