title: Asthma and height in twins: a cohort and within-pair analyses study.
abstract: In singletons, asthma may be associated with shorter height and delayed growth during adolescence. Yet, these studies do not account for heritability of asthma, puberty/menarche, and height. We aimed to study the association between asthma and puberty in boys and menarche in girls, and height, in a cohort of twins and subsequently in same-sex twin pairs discordant for asthma. From a Swedish twin cohort, parent- and self-reported data on asthma, puberty/menarche, and height were collected. Pubertal staging was established via the Petersen index. Logistic and linear regression was used to estimate associations between asthma and puberty/menarche and height, respectively. For within-pair analyses in twins discordant for asthma, conditional logistic and linear regression were used. Data on 2,658 (49.1% boys) twins were included. Among boys, asthma prevalence was 8.2% at 8-9 years and 10.2% at 13-14 years. Corresponding numbers for girls were 4.2% and 4.9%, respectively. In the entire cohort, no statistically significant associations were found between current asthma and puberty/menarche. Boys with asthma were shorter than boys without asthma at 8-9 years (on average, 1.86 [0.17-3.56] cm, p = .03) and at 13-14 years (on average, 2.94 [0.98-4.91] cm, p = .003) but not at 19-20 years. No such associations were found for girls. Within same-sex twin pairs discordant for asthma, no statistically significant associations were found for either sex. Twin boys, but not girls, with asthma were shorter than those without asthma. Non-statistically significant estimates from within-pair analyses suggest the association is partly confounded by genetic or familial environmental factors.
authors.affiliation: Department of Medical Epidemiology and Biostatistics,Karolinska Institutet,Stockholm,Sweden.
authors.forename: Jennifer L P
authors.initials: JL
authors.lastname: Protudjer
authors.affiliation: Department of Medical Epidemiology and Biostatistics,Karolinska Institutet,Stockholm,Sweden.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Lundholm
authors.affiliation: Department of Medical Epidemiology and Biostatistics,Karolinska Institutet,Stockholm,Sweden.
authors.forename: Catarina
authors.initials: C
authors.lastname: Almqvist
mesh_terms: D000293:Adolescent; D050499:Adrenarche / Q000235:genetics*; D000328:Adult; D001249:Asthma / Q000453:epidemiology / Q000235:genetics*; D001827:Body Height / Q000235:genetics*; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008572:Menarche / Q000235:genetics*; D012737:Sex Factors; D013548:Sweden / Q000453:epidemiology; D014429:Twins, Dizygotic / Q000235:genetics*; D014430:Twins, Monozygotic / Q000235:genetics*
keywords: twins