Give the cause and one symptom of following diseases.
Asthma

Explanation

Asthma : It is due to the allergic reaction to foreign particles that affect respiratory tract. An asthmatic attacks may be triggered by the exposure to an allergen, such as tree , grass or weed pollen, dust, mites, cockroaches etc.
Symptoms : The symptoms include coughing, wheezing and difficulty in breathing . It is all due to excess of mucus in wall of respiratory tract