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

Summary Background 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. Objective The purpose of this study was to identify susceptibility loci for allergic rhinoconjunctivitis. Methods 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. Results 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 × 10 −4 ) while one on chromosome 17 close to marker D17S921 almost reaches this level (LOD=2.17, P <8 × 10 −4 , Table 3 ). Single‐point linkage analysis for allergic rhinoconjunctivitis Marker Map position (cM) * LOD P‐ value † D3S1278 129.73 2.28 <6 × 10 −4 D3S1267 139.12 1.63 <0.004 D4S1625 145.98 1.18 <0.01 D4S1652 208.07 1.77 <0.003 D6STNFa 63.41 1.14 <0.05 D9S257 91.87 1.10 <0.05 D17S921 36.12 2.17 <8 × 10 −4 D17S1294 50.74 1.78 <0.005 D18S843 28.1 1.23 <0.001 Position in centiMorgan (cM) of markers from p‐ter to q‐ter based on the Marshfield map ( http//research.marshfieldclinic.org/genetics ). P ‐values estimated using P (LOD)=0.5 × (χ 2 1 > 2 ln 10 × LOD). Conclusion Our results support the linkage to allergic rhinoconjunctivitis on 3q13, 6p23–p24 and 9q34.3 shown in previous investigations.