Cristina D'Ippolito

Heritability and shared genetic effects of asthma and hay fever: an Italian study of young twins.

A number of studies have provided evidence of a significant familial aggregation for both asthma and hay fever, and have reported a substantial comorbidity between the two conditions. However, far fewer, especially in Italy, have aimed at clarifying the origins of such comorbidity. The main aims of the present study were (a) to estimate heritability of asthma and hay fever, (b) to measure the association between asthma and hay fever at the individual level, and (c) to assess the extent to which genetic and environmental factors, shared by the two conditions, mediate this association. The twin method was used. The study sample was derived from the Italian Twin Registry, and included 392 twin pairs aged 8 to 17 years. Data collection was performed through parent self-administered questionnaire. Bivariate structural equation twin modeling was applied to asthma and hay fever. Genetic factors accounted for 92% and 78% of the variance in liability to asthma and hay fever, respectively, with the remaining contributions due to unique environmental influences. The within-individual association between asthma and hay fever was substantial. The genetic correlation between the two conditions was .58, whereas no evidence of overlapping unique environmental effects was found. In conclusion, this study showed a high heritability of asthma and hay fever in the Italian child and adolescent population. It also indicated that asthma and hay fever share, to a large extent, a common genetic background, and environmental factors are not relevant to explain the comorbidity.

Clinical evolution of celiac disease in Italy 1982-2002.

Goals: The aim of this work is to assess how the clinical features of celiac disease have changed in Italy after the widespread introduction of serologic tests in 1993. Study: Twenty Italian Clinical Centers collected information from 1982 until 2002 on 1968 patients older than 18 years diagnosed with celiac disease. Results: The results show that the incidence of atypical and silent cases of celiac disease has increased after the wider availability of serological test, which has allowed earlier diagnosis and treatment. Conclusions: This paper provides a view on the evolution of the clinical features of celiac disease in Italy over 2 decades. The relevance of the analysis is supported by the fact that Italy is one of the countries with the highest incidence of celiac disease. These findings underline the importance of a timely diagnosis of celiac disease.

Genetic and environmental influences on adult human height across birth cohorts from 1886 to 1994

Human height variation is determined by genetic and environmental factors, but it remains unclear whether their influences differ across birth-year cohorts. We conducted an individual-based pooled analysis of 40 twin cohorts including 143,390 complete twin pairs born 1886–1994. Although genetic variance showed a generally increasing trend across the birth-year cohorts, heritability estimates (0.69-0.84 in men and 0.53-0.78 in women) did not present any clear pattern of secular changes. Comparing geographic-cultural regions (Europe, North America and Australia, and East Asia), total height variance was greatest in North America and Australia and lowest in East Asia, but no clear pattern in the heritability estimates across the birth-year cohorts emerged. Our findings do not support the hypothesis that heritability of height is lower in populations with low living standards than in affluent populations, nor that heritability of height will increase within a population as living standards improve. DOI: http://dx.doi.org/10.7554/eLife.20320.001

Association between birthweight and later body mass index : an individual-based pooled analysis of 27 twin cohorts participating in the CODATwins project

Abstract Background There is evidence that birthweight is positively associated with body mass index (BMI) in later life, but it remains unclear whether this is explained by genetic factors or the intrauterine environment. We analysed the association between birthweight and BMI from infancy to adulthood within twin pairs, which provides insights into the role of genetic and environmental individual-specific factors. Methods This study is based on the data from 27 twin cohorts in 17 countries. The pooled data included 78 642 twin individuals (20 635 monozygotic and 18 686 same-sex dizygotic twin pairs) with information on birthweight and a total of 214 930 BMI measurements at ages ranging from 1 to 49 years. The association between birthweight and BMI was analysed at both the individual and within-pair levels using linear regression analyses. Results At the individual level, a 1-kg increase in birthweight was linearly associated with up to 0.9 kg/m2 higher BMI (P < 0.001). Within twin pairs, regression coefficients were generally greater (up to 1.2 kg/m2 per kg birthweight, P < 0.001) than those from the individual-level analyses. Intra-pair associations between birthweight and later BMI were similar in both zygosity groups and sexes and were lower in adulthood. Conclusions These findings indicate that environmental factors unique to each individual have an important role in the positive association between birthweight and later BMI, at least until young adulthood.