Mutations in the Human Laminin beta 2 (LAMB2) Gene and the Associated Phenotypic Spectrum
HUMAN MUTATION
Authors: Matejas, Verena; Hinkes, Bernward; Alkandari, Faisal; Al-Gazali, Lihadh; Annexstad, Ellen; Aytac, Mehmet B.; Barrow, Margaret; Blahova, Kveta; Bockenhauer, Detlef; Cheong, Hae Il; Maruniak-Chudek, Iwona; Cochat, Pierre; Doetsch, Joerg; Gajjar, Priya; Hennekam, Raoul C.; Janssen, Francoise; Kagan, Mikhail; Kariminejad, Ariana; Kemper, Markus J.; Koenig, Jens; Kogan, Jillene; Kroes, Hester Y.; Kuwertz-Broeking, Eberhard; Lewanda, Amy F.; Medeira, Ana; Muscheites, Jutta; Niaudet, Patrick; Pierson, Michel; Saggar, Anand; Seaver, Laurie; Suri, Mohnish; Tsygin, Alexey; Wuehl, Elke; Zurowska, Aleksandra; Uebe, Steffen; Hildebrandt, Friedhelm; Antignac, Corinne; Zenker, Martin
Abstract
Mutations of LAMB2 typically cause autosomal recessive Pierson syndrome, a disorder characterized by congenital nephrotic syndrome, ocular and neurologic abnormalities, but may occasionally be associated with milder or oligosymptomatic disease variants. LAMB2 encodes the basement membrane protein laminin beta 2, which is incorporated in specific heterotrimeric laminin isoforms and has an expression pattern corresponding to the pattern of organ manifestations in Pierson syndrome. Herein we review all previously reported and several novel LAMB2 mutations in relation to the associated phenotype in patients from 39 unrelated families. The majority of disease-causing LAMB2 mutations are truncating, consistent with the hypothesis that loss of laminin beta 2 function is the molecular basis of Pierson syndrome. Although truncating mutations are distributed across the entire gene, missense mutations are clearly clustered in the N-terminal LN domain, which is important for inter-molecular interactions. There is an association of missense mutations and small in frame deletions with a higher mean age at onset of renal disease and with absence of neurologic abnormalities, thus suggesting that at least some of these may represent hypomorphic alleles. Nevertheless, genotype alone does not appear to explain the full range of clinical variability, and therefore hitherto unidentified modifiers are likely to exist. Hum Mutat 31:992-1002, 2010. (c) 2010 Wiley-Liss, Inc.
Residential Proximity to Major Roadways at Birth, DNA Methylation at Birth and Midchildhood, and Childhood Cognitive Test Scores: Project Viva (Massachusetts, USA)
ENVIRONMENTAL HEALTH PERSPECTIVES
Authors: Peng, Cheng; den Dekker, Martijn; Cardenas, Andres; Rifas-Shiman, Sheryl L.; Gibson, Heike; Agha, Golareh; Harris, Maria H.; Coull, Brent A.; Schwartz, Joel; Litonjua, Augusto A.; DeMeo, Dawn L.; Hivert, Marie-France; Gilman, Matthew W.; Sagiv, Sharon K.; de Kluizenaar, Yvonne; Felix, Janine F.; Jaddoe, Vincent W.; Oken, Emily; Duijts, Liesbeth; Gold, Diane R.; Baccarelli, AndreaA.
Abstract
BACKGROUND: Epigenetic variability is hypothesized as a regulatory pathway through which prenatal exposures may influence child development and health. OBJECTIVE: We sought to examine the associations of residential proximity to roadways at birth and epigenome-wide DNA methylation. We also assessed associations of differential methylation with child cognitive outcomes. METHODS: We estimated residential proximity to roadways at birth using a geographic information system (GIS) and cord blood methylation using Illumina's HumanMethylation450-array in 482 mother child pairs in Project Viva. We identified individual CpGs associated with residential proximity-to-roadways at birth using robust linear regression [false discover), rate (FDR) <0.05]. We also estimated association between proximity-to-roadways at birth and methylation of the same sites in blood samples collected at age 7-11 y = 415). We ran the same analyses in the Generation R Study for replication (N =641). In Project Viva, we investigated associations of differential methylation at birth with midchildhood cognition using linear regression. RESULTS: Living closer to major roadways at birth was associated with higher cord blood (and-more weakly-midchildhood blood) methylation of four sites in LAMB2. For each halving of residential-proximity-to-major-roadways, we observed a 0.82% increase in DNA methylation at cg05654765 [95% confidence interval (CI): (0.54%, 1.10%)], 0.88% at cg14099457 [95% CI: (0.56%, 1.19%)], 0.19% at cg03732535 [95% CI: (0.11%, 0.28)], and 1.08% at cg02954987 [95% CI: (0.65%, 1.51%)]. Higher cord blood methylation of these sites was associated with lower midchildhood nonverbal cognitive scores. Our results did not replicate in the Generation R Study. CONCLUSIONS: Our discovery results must be interpreted with caution, given that they were not replicated in a separate cohort. However, living close to major roadways at birth was associated with cord blood methylation of sites in LAMB2 a gene known to he linked to axonal development-in our U.S. cohort. Higher methylation of these sites associated with lower nonverbal cognitive scores at age 7-11 y in the same children.