Study to Investigate Genetic Causes of Severe Early Childhood Onset Obesity.

This is a clinical and genomic study designed to investigate monogenic causes of severe early childhood obesity. Participants with severe early onset obesity will be identified by screening of the clinical database or referred for the study. These subjects will be invited to participate in the study. After obtaining informed consent, the investigators will obtain history on the proband and the family, and perform a brief examination in addition to collecting genetic material. Targeted sequencing of genes associated with monogenic and syndromic forms of obesity will be performed using next-generation sequencing. In selected individuals with favorable family history, exome or whole genome sequencing will be performed. Functional analysis of newly identified variants will be performed where possible.