Frequency and specific sensitization to inhalant allergens within nuclear families of children with asthma and/or rhinitis

Objective: The purpose of this study was to investigate the frequency of allergy in 85 families of pediatric patients with asthma and/or rhinitis. Methods: Families enrolled were drawn according to a table of randomization, from those whose children were referred the outpatient clinic of the Pulmonology Department of Gaslini Institute (Genoa, Italy). In patients and in both their mothers and fathers, allergic sensitization to the three most common classes of inhalant allergens (house dust mites, pollens, and animal danders) was evaluated by skin prick test. Results: As compared with their parents, children showed a similar prevalence of positive skin prick test (50.0% and 58.8%, respectively; χ² = 1.4; P > .1), but a significantly higher frequency of specific sensitization to house dust mites, pollens, or pets (P <.05, each χ²). These differences were at least partially related to the higher frequency of polysensitization (ie, sensitization to more than one class of allergens) in children than in their parents [χ² = 4.2, odds ratio (OR) = 2.3, 95% confidence interval (CI(95%)) = 1.0 to 5.1; P <.05). In addition, both in children (χ² = 5.8, OR = 11.3, CI(95%) = 1.4 to 81.5; P <.05] and in their parents (χ² = 7.4, OR = 4.8, CI(95%) = 1.5 to 16.7; P <.01), allergy to pollens was less frequent in monosensitized than in polysensitized families, while the prevalence of sensitization to house dust mites was similar in monosensitized and in polysensitized families. The analysis of the role of parental sensitization in the development of allergy in the offspring demonstrated that the prevalence of allergic children: (1) seemed to be higher, without reaching statistical significance, in families with sensitized parents than in those with non-sensitized parents (χ² = 0.41, P > .1) and (2) was higher in families with one or both polysensitized parents than in those with one or both monosensitized parents (χ² = 4.5, OR = 4.0, CI(95%) = 1.1 to 15.6; P <.05). In addition, within each family, the coincidence of sensitization to house dust mites was more frequent than that to pollens (60.0% and 36.0%, respectively; χ² = 7.6, OR = 4.5, CI(95%) = 1.5 to 14.3; P <.01), and it was not influenced by the number of parents sensitized to same allergen. Conclusion: These data support the concept that, in addition to genetic predisposition, other factors (ie, environmental exposure) may influence the development of specific sensitization in children with respiratory symptoms. The different sensitization found in this study between children and their parents occurred in a generation span, so as it is more likely to be related to environmental changes than to genetic factors.