RESUMO
BACKGROUND: While previous studies have probed the genetics of asthma and serum IgE levels, there have been no studies on the genetics of allergic conjunctivitis. This paper describes the initial phase of a genetic study of allergic conjunctivitis. METHODS: Approximately 117 families with probands with allergic conjunctivitis were recruited generating 245 affected sib pairs. Each family member completed a detailed questionnaire on atopic symptoms, and results from skin testing were obtained. Genomic DNA was extracted and genotyped using thirty-five polymorphic markers spanning human chromosomes 5, 6, 11, 12, 16 and 17. Heritability was assessed using the POINTER program, and nonparametric linkage analysis using the BETA program. RESULTS: Evidence for genetic linkage of allergic conjunctivitis was obtained for chromosomes 5, 16 and 17. Weak linkage was detected for chromosome 6 when studies were restricted to specific allergens. No evidence for linkage was detected for chromosomes 11 and 12. CONCLUSIONS: Consistent with heritability analysis discussed in this paper, genetic linkage for allergic conjunctivitis is shown to differ from that reported for atopic asthma. This indicates that there are likely to be organ-specific disease susceptibility genes, which together with general atopy genes target the allergic response to specific mucosal tissues.
