July 11, 2006

Heritability of physical and psychological traits in 6,148 Sardinians

A new study in PLoS Genetics has estimated heritabilities of various traits over a large population of Sardinians. Please note that heritabilities calculated in one population should not be extended to other populations. If, e.g., there is a lot of environmental variation in nutrition in a population, then stature will be least affected by hereditary factors. Conversely, if all individuals are fed well, then the largest part of individual differences will be attributed to hereditary factors.

PLoS Genetics (Early Online Release)

Heritability of Cardiovascular and Personality Traits in 6,148 Sardinians

Giuseppe Pilia et al.


In large samples, phenotypic similarities between relatives yield information on the overall contribution of genes to trait variation. Large samples are especially important to compare heritability between subgroups such as young and old, or males and females. We recruited a cohort of 6,148 participants, aged 14-102, from 4 clustered towns in Sardinia. The cohort includes 34,469 relative pairs. To extract genetic information, we implemented software for variance components heritability analysis, designed to handle large pedigrees, analyze multiple traits simultaneously and model heterogeneity. Here, we report heritability analyses for 98 quantitative traits, focusing on facets of personality and cardiovascular function. We also summarize results of bivariate analyses for all pairs of traits and of heterogeneity analyses for each trait. We found a significant genetic component for every trait. On average genetic effects explained 40% of the variance for 38 blood tests, 51% for 5 anthropometric measures, 25% for 20 measures of cardiovascular function, and 19% for 35 personality traits. Four traits showed significant evidence for an X-linked component. Bivariate analyses suggested overlapping genetic determinants for many traits, including multiple personality facets and several traits related to the metabolic syndrome; but we found no evidence for shared genetic determinant that might underlie the reported association of some personality traits and cardiovascular risk factors. Models allowing for heterogeneity suggested that, in this cohort, the genetic variance was typically larger in females and in younger individuals, but interesting exceptions were observed. For example, narrow heritability of blood pressure was ~26% in individuals >42 years old, but only ~8% in younger individuals. Despite the heterogeneity in effect sizes, the same loci appear to contribute to variance in young and old and in males and females. In summary, we find significant evidence for heritability of many medically important traits, including cardiovascular function and personality. Evidence for heterogeneity by age and sex suggest that models allowing for these differences will be important in mapping quantitative traits.


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