Genome-wide linkage analysis of allergic rhinoconjunctivitis in a Swedish population

Allergic rhinoconjunctivitis is a common complex disorder characterized by itching and irritation in the nose, bouts of sneezing, watery rhinorrhoea, nasal congestion and itchy eyes with tears and swelling. Like other atopic disorders such as allergic asthma and atopic dermatitis, the development involves complex interactions of genes and environmental factors. The purpose of this study was to identify susceptibility loci for allergic rhinoconjunctivitis. We conducted a genome-wide linkage analysis using a non-parametric, affected-relative-pair method. The 250 families used were collected originally for an atopic dermatitis linkage study. Three regions showed favour in evidence of linkage to allergic rhinoconjunctivitis: 3q13 (D3S1278: logarithm of odds ratio (LOD)=1.64, P < 0.003), 4q34-35 (D4S1652: LOD=1.49, P < 0.005) and 18q12 (D18S535: LOD=1.94, P < 0.002). In addition, four regions showed weaker evidence in favour of linkage: 6p22-24 (D6S1959: LOD=1.39, P < 0.006), 9p11-q12 (D9S1118: LOD=1.15, P < 0.02), 9q33.2-34.3 (D9S915: LOD=1.29, P < 0.01) and 17q11.2 (D17S1294: LOD=1.13, P < 0.02). In single-point analysis, one locus on chromosome 3 close to marker D3S1278 reaches the suggestive level (LOD=2.28, P < 6 x 10(-4)) while one on chromosome 17 close to marker D17S921 almost reaches this level (LOD=2.17, P < 8 x 10(-4), Table 3). Our results support the linkage to allergic rhinoconjunctivitis on 3q13, 6p23-p24 and 9q34.3 shown in previous investigations.