NOT a feature of childhood asthma is –
Asthma 

Bronchial asthma is a disease characterized by an increased responsiveness of airways to a variety of stimulus and causes recurrent attacks of wheezing, breathlessness, chest tightness and cough.
The symptoms are due to bronchoconstriction which is reversible in a large majority of the cases, either spontaneously or in response to treatment.
Asthma is the commonest chronic illness during childhood.
It is a type I hypersensitivity, which is mediated by IgE IgE is raised (not IgG)

Risk factors

Family history of asthma
Family history of atopic disease (Atopic dermatitis, allergic rhinitis).
Bronchiolitis during infancy.
Sensitization to allergenes (dust mite, animal danders, cockroaches and Alternaria) during childhood.
Passive smoking

The response of Asthmatic patients to exercise -
Mild exercise i.e., running for 1-2 minutes caused bronchodilation in asthmatic patients and can reduce wheezing (wheezing is produced due to obstruction in bronchi). Severe exercise will cause bronchoconstriction in virtually all asthmatic patients and will aggravate wheezing.
Prognosis of Asthma -
The prognosis of young asthmatic children is generally good. Longitudinal studies indicate that in patients who have mild asthma the remission rate is about 50% i.e., 50% of them will be asthma free in their adulthood.
In severe asthma characterized by chronic steroid-dependent disease, the remission rate is very less. About 95% of them will develop into asthmatic adults.
History of atopic dermatitis
Raised IgG level
Improves with age
Absence of wheezing after exercise