INTRODUCTION
Asthma is the most common non-communicable diseases among children,
characterized by shortness of breath, rapid breathing, chest tightness
and wheezing.1,2 The prevalence of childhood asthma
has increased worldwide. Asthma is one of top reasons why children miss
school days and visit emergency department, and it can affect children’s
long-term health by impairing lung function and increasing risk of
developing Chronic Obstructive Pulmonary Disease
(COPD).3 The etiology of asthma is not fully
understood. Thus, identifying risk factors for childhood asthma could be
beneficial to increase early detection of the disease and prevent
adverse outcomes later in life.
Asthma can be genetically heritable and the heritability estimated by
twin studies ranges from 35% to 70%.4 Although,
genome-wide research has identified a number of asthma susceptibility
loci, they only account for a small fraction of the
heritability.5,6 There are still genetic risk factors
waiting to be unveiled. A family history could provide useful
information for gene susceptibility, if shared environmental factors
were controlled.7 Parents with asthma has been widely
reported to contribute to increasing offspring’s asthma
risk.8,9 However, the relative roles of maternal
asthma and paternal asthma on their offspring’s asthma risk is
controversial. Some studies found that a maternal had stronger impact
than a paternal, whereas others had the opposite
findings.10 In addition, grandparents are relatives
who share 25% of a person’s genes.11 Rare studies
have reported the impact of a grandparental on a child’s risk of
developing asthma.
In this study, we aimed to investigate the multi-generational hereditary
patterns of asthma. We estimated the familial risks of asthma for
children who had family members (parents, maternal grandparents and
paternal grandparents) affected by asthma after controlling for
potential environmental risk factors (e.g. environment tobacco exposure,
ambient air pollution and pet keeping).12-14 In
addition, we also estimated the impact of parents on the association
between grandparental asthma and childhood asthma.