Obesity: The Rule or Not

Whether overweight and obesity should be included in the clinical phenotype of subjects with Klinefelter syndrome is still an open issue. In the present review, we presented and discussed available data on the topic. PubMed and Google Scholar were searched on November 2019. Obesity was defined as a body mass index ≥95th percentile for the same age and sex in children/teens and ≥30 kg/m2 in adults; studies reporting data dichotomously were included. A limited number of papers were found, with heterogeneous findings. According to unpublished data in adult and pediatric subjects here reported, the prevalence of obesity in subjects with Klinefelter syndrome at presentation was not higher compared to the general population. These data do not support the view that obesity is a common phenotype in subjects with Klinefelter syndrome or that this genetic disorder should be considered as a secondary cause of obesity. However, the reliability of using body mass index in these subjects may be limited, therefore further epidemiological studies are needed.