Asthma is a major public health problem among Puerto Ricans. Little is known, however, about the effect of heredity and environment on the development and severity of asthma in this population. This study will examine the relationship between asthma and certain genetic and environmental factors in Puerto Rican children.

Asthma is a chronic disease that causes constriction of the airways. People with asthma may experience wheezing, coughing, chest tightness, and trouble breathing. Although asthma is a major public health problem among Puerto Ricans, little research has been done to determine the influence of heredity and environment on the disease in this population. To learn more about these relationships, this study will examine the effects of certain genes and allergens on the development and severity of asthma in Puerto Rican children.

This observational study will recruit both children with asthma and children without asthma. Participants will meet with study staff twice during the study. The first visit will take place at participants' homes. Participants will complete questionnaires about demographics, respiratory and general health, and household characteristics. Lung function testing, collection of blood samples, and collection of household dust samples will also take place at the home-based visit. The second visit will take place at the study site. At this visit, participants will undergo allergy tests on the skin and a methacholine challenge test to assess their airway responsiveness and asthma severity. The methacholine challenge test will involve inhaling mist through a mouthpiece and blowing forcefully into a special apparatus called a spirometer. Parents will be asked to provide information about their children's exposure to pets in early life. Each visit will last approximately 1.5 hours and will be scheduled close to the date on which a participant enters the study.

Inclusion Criteria:

For participants with asthma:

• Diagnosis of asthma
• History of wheezing within 12 months prior to study entry
• Has four grandparents that were born in Puerto Rico

For participants without asthma:

• No diagnosis of asthma
• No history of wheezing within 12 months prior to study entry
• Has four grandparents that were born in Puerto Rico

Exclusion Criteria:

• Significant pulmonary disease other than asthma
• Hospitalization in the neonatal intensive care unit and requiring ventilatory support
• History of cigarette smoking for more than 5 pack-years ([number of packs smoked per day] x [number of years of smoking])

Children of Puerto Rican descent (having four Puerto Rican grandparents) living in Hartford (Connecticut) and in the metropolitan areas of San Juan and Caguas in the island of Puerto Rico.