Individual differences in puberty onset in girls: Bayesian estimation of heritabilities and genetic correlations

We report heritabilities for individual differences in female pubertal development at the age of 12. Tanner data on breast and pubic hair development in girls and data on menarche were obtained from a total of 184 pairs of monozygotic and dizygotic twins. Genetic correlations were estimated to determine to what extent the same genes are involved in different aspects of physical development in puberty. A Bayesian estimation approach was taken, using Markovchain Monte Carlo simulation to estimate model parameters. All three phenotypes were to a significant extent heritable and showed high genetic correlations, suggesting that a common set of genes is involved in the timing of puberty in general. However, gonadarche (menarche and breast development) and adrenarche (pubic hair) are affected by different environmental factors, which does not support the three phenotypes to be regarded as indicators of a unitary physiological factor. © 2006 Springer Science+Business Media, Inc

Migrainomics-identifying brain and genetic markers of migraine

Migraine is one of the world's most prevalent and disabling disorders and imposes an enormous socioeconomic burden. The exact causes of migraine are unknown, and no recognizable diagnostic pathological changes have been identified. Specific identifiable markers of migraine would aid diagnosis and could provide insight into the pathogenesis of the condition, with the potential to direct development of new therapeutics. In the past few years, advances in neuroimaging and genetic studies have provided the most substantial progress towards the identification of markers. A growing number of brain imaging studies have provided important insights into the brain mechanisms that underlie migraine symptoms during and between migraine attacks. Similarly, large-scale genome-wide association studies have identified genetic variants associated with the common forms of migraine-migraine with aura and migraine without aura. In total, 44 independent single-nucleotide polymorphism loci have been robustly associated with the risk of migraine and provide new evidence for the involvement of vascular mechanisms. Both imaging and genetics, therefore, have excellent potential as markers of migraine. In this Review, we provide a summary of results regarding current and potential neuroimaging and genetic markers of migraine, consider what conclusions can be drawn from these markers about migraine mechanisms and discuss the potential of combining imaging and genetics