A fairly recent meta-analysis of studies examining the association between adult obesity and polymorphisms of the FTO gene (Peng et al., 2011). The paper looked at 59 studies and concluded that, "FTO may represent a low-penetrance susceptible gene for obesity risk", although the association was weaker (or non-existent) for some ethnic groups.
Are other polymorphic genes which are currently known to be more strongly associated with obesity risk than the FTO gene?