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Obesity rates have escalated to the point of a global pandemic with varying prevalence across ethnic groups. These differences are partially explained by lifestyle factors in addition to genetic predisposition to obesity. This review provides a comprehensive examination of the ethnic differences in the genetic architecture of obesity. Using examples from evolution, heritability, admixture, monogenic and polygenic studies of obesity, we provide explanations for ethnic differences in the prevalence of obesity. The debate over definitions of race and ethnicity, the advantages and limitations of multi-ethnic studies and future directions of research are also discussed. Multi-ethnic studies have great potential to provide a better understanding of ethnic differences in the prevalence of obesity that may result in more targeted and personalized obesity treatments., (© 2017 World Obesity Federation.)

Aim: Several different genetic defects have been found to result in the characteristic phenotypic expression of Prader-Willi syndrome (PWS)., Methods: We performed a retrospective analysis of 67 cases of molecularly confirmed PWS diagnosed from January 1980 through July 2006 in five medical centres in Taiwan. Clinical manifestations were compared between patients with deletion and those with maternal uniparental disomy (UPD)., Results: Deletion was present in 56 (84%), UPD in 10 (15%), and a probable imprinting centre deletion or imprinting defect in 1 (1%). PWS with deletion was more likely than that with UPD to be characterized by hypogonadism (p < 0.001), small hands and feet (p < 0.001), and hypopigmentation (p < 0.002). Both maternal (p = 0.015) and paternal age (p = 0.021) were higher in the UPD group. No other clinical features differed significantly different between the two groups., Conclusion: In contrast to most Western populations with a higher incidence of UPD, this study of PWS in Taiwan shows a higher incidence of deletion. There may be subtle phenotypic differences between the UPD and deletion genotypes, but its not clear that these are important clinically.

We report on 10 African Americans with Prader-Willi syndrome whose features differ from those of white patients with this condition. Growth is less affected, hand and foot lengths usually are normal, and the facies are atypical; this may lead to underdiagnosis in this population. We encourage clinicians to recognize these phenotypic differences so that diagnosis is not overlooked.