Association between obesity and asthma in a twin cohort.
BACKGROUND
Obesity is linked to asthma in a yet poorly understood manner. We examined the relationship between obesity and asthma in a population-based sample of twins.


METHODS
From the cohorts born between 1953 and 1982, who were enrolled in The Danish Twin Registry, a total of 29 183 twin individuals participated in a nationwide questionnaire study, where data on height, weight and asthma were collected. Latent factor models of genetic and environmental effects were fitted using maximum likelihood methods.


RESULTS
The age-adjusted risk of asthma was increased both in obese females, OR = 1.96 (1.45-2.64), P < or = 0.001 and in obese males, OR = 1.59 (1.08-2.33), P = 0.02. According to best-fitting models, the heritability for obesity was 81% in males and 92% in females, whereas the heritability for asthma was 78% and 68% in males and females respectively. The age-adjusted genetic liabilities to obesity and asthma were significantly correlated only in females, r = 0.28 (0.16-0.38).


CONCLUSIONS
Obese subjects have an increased risk for asthma, which in females seems partly because of common genes.
Thomsen
S F
SF
Department of Respiratory Medicine, Bispebjerg Hospital, Copenhagen, Denmark.
Ulrik
C S
CS
Kyvik
K O
KO
Sørensen
T I A
TI
Posthuma
D
D
Skadhauge
L R
LR
Steffensen
I
I
Backer
V
V
D000328:Adult; D017677:Age Distribution; D001249:Asthma / Q000453:epidemiology* / Q000235:genetics*; D015992:Body Mass Index; D015331:Cohort Studies; D015897:Comorbidity; D003718:Denmark / Q000453:epidemiology; D004200:Diseases in Twins / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D008297:Male; D009765:Obesity / Q000453:epidemiology* / Q000235:genetics*; D011159:Population Surveillance / Q000379:methods; D015995:Prevalence; D012307:Risk Factors; D012737:Sex Factors; D011795:Surveys and Questionnaires; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic