OBJECTIVETo discuss the related impact of genetic factors in the incidence of bronchial asthma (BA) and allergic rhinitis (AR) in Nantong region, China.

METHODSBy random sampling method, investigation and research on the incidence of genetic epidemiology were carried out in the population of 95 300 on AR and BA.

RESULTSThe rate of patients with allergic rhinitis with asthma was 25.92% (296/1142), the rate of asthma patients with allergic rhinitis was 40.49% (296/731). The prevalences of AR complicated with BA were 8.19% (280/3418), 3.08% (154/5002) and 3.16% (85/2687) in the first-, second-and third-degree relatives of the probands respectively, while the prevalences of BA complicated with AR were 15.81% (466/2947), 4.61% (229/4967) and 2.51% (134/5345) in the first-, second- and third-degree relatives of the probands respectively, higher than those in the controls (P < 0.05). The weighted mean heritability of AR in BA patients was 94.2% ± 1.9%, while the weighted mean heritability of BA in AR patients was 81.8% ± 2.1%, more than 60%, suggesting that both AR and BA were relevant with genetics.

CONCLUSIONSThe incidence of BA and AR has obvious relevance, supporting the theory that the two diseases are an united airway disease and relevant with polygene heredity.