Human laminin β2 deficiency causes congenital nephrosis with mesangial sclerosis and distinct eye abnormalities

Congenital nephrotic syndrome (CNS) is clinically and genetically heterogeneous, with mutations in WT1, NPHS1 and NPHS2 accounting for part of cases. We recently delineated a new autosomal recessive entity comprising CNS with diffuse mesangial sclerosis and distinct ocular anomalies with microcoria...

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Published in:Human molecular genetics 2004-11, Vol.13 (21), p.2625-2632
Main Authors: Zenker, Martin, Aigner, Thomas, Wendler, Olaf, Tralau, Tim, Müntefering, Horst, Fenski, Regina, Pitz, Susanne, Schumacher, Valérie, Royer-Pokora, Brigitte, Wühl, Elke, Cochat, Pierre, Bouvier, Raymonde, Kraus, Cornelia, Mark, Karlheinz, Madlon, Henry, Dötsch, Jörg, Rascher, Wolfgang, Maruniak-Chudek, Iwona, Lennert, Thomas, Neumann, Luitgard M., Reis, André
Format: Article
Language:English
Subjects:
Biological and medical sciences
Fundamental and applied biological sciences. Psychology
Genetics of eukaryotes. Biological and molecular evolution
Molecular and cellular biology
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Summary:Congenital nephrotic syndrome (CNS) is clinically and genetically heterogeneous, with mutations in WT1, NPHS1 and NPHS2 accounting for part of cases. We recently delineated a new autosomal recessive entity comprising CNS with diffuse mesangial sclerosis and distinct ocular anomalies with microcoria as the leading clinical feature (Pierson syndrome). On the basis of homozygosity mapping to markers on chromosome 3p14–p22, we identified homozygous or compound heterozygous mutations of LAMB2 in patients from five unrelated families. Most disease-associated alleles were truncating mutations. Using immunohistochemistry and western blotting we could demonstrate that the respective LAMB2 mutations lead to loss of laminin β2 expression in kidney and other tissues studied. Laminin β2 is known to be abundantly expressed in the glomerular basement membrane (GBM) where it is thought to play a key role in anchoring as well as differentiation of podocyte foot processes. Lamb2 knockout mice were reported to exhibit congenital nephrosis in association with anomalies of retina and neuromuscular junctions. By studying ocular laminin β2 expression in unaffected controls, we detected the strongest expression in the intraocular muscles corresponding well to the characteristic hypoplasia of ciliary and pupillary muscles observed in patients. Moreover, we present first clinical evidence of severe impairment of vision and neurodevelopment due to LAMB2 defects. Our current data suggest that human laminin β2 deficiency is consistently and specifically associated with this particular oculorenal syndrome. In addition, components of the molecular interface between GBM and podocyte foot processes come in the focus as potential candidates for isolated and syndromic CNS.
ISSN:0964-6906
1460-2083
DOI:10.1093/hmg/ddh284