Older siblings worsen effect of FLG gene mutations on childhood eczema
MedWire News: Study results show that for children who have eczema predisposing mutations in the filaggrin gene (FLG) having older siblings significantly increases the risk for developing childhood eczema.
Previous research findings have suggested that a protective effect of elder siblings on eczema development exists, in line with the hygiene hypothesis, say researchers.
“However, findings are not consistent, and there might exist different causal pathways for the development of eczema,” write Claudia Cramer (University of Düsseldorf, Germany) and team. This may particularly apply to those with eczema predisposing genetic mutations such as those in FLG.
Cramer and colleagues investigated interactions between FLG mutations and eczema development in two German birth cohorts; LISAplus (n=1039) and GINIplus (n=1828).
The children were genotyped for the common FLG mutations R501X and 2282del4 and followed-up for incident eczema until the age of 6 years. The researchers found that 6.7% and 6.0% of the children in the LISAplus and GINIplus cohorts had FLG mutations, respectively.
As reported in the Journal of Allergy and Clinical Immunology, no protective effect of elder siblings on eczema development was observed, even after adjusting for early day care attendance.
In the total cohort, presence of FLG mutations increased the relative risk for developing eczema by 45% and having siblings by 6%, but these risk increases were only of borderline significance. However, children with FLG mutations who also had older siblings had a significant 94% increase in relative risk for developing eczema compared with children with no siblings or FLG mutations.
Following adjustment for early day care attendance, children in the LISAplus and GINIplus cohorts with FLG mutations and older siblings had a 3.27- and 2.41-fold increased risk for developing early childhood eczema, respectively.
“Our results give evidence for complex skin-driven pathogenic mechanisms that might be different depending on children’s genetic backgrounds,” write the authors.
“Further studies must replicate our findings and should focus on interactions between FLG mutations and environmental factors,” they conclude.
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By Helen Albert