Notably, recent investigations report a new highly penetrant form of obesity (or underweight) due to deletions (or reciprocal duplications) on chromosome 16p11.2, that is often associated with hyperphagia and intellectual disabilities [50, 102], indicating a pathological connection between weight disorders and nervous system diseases in genomic level. The reciprocal impact of these 16p11.2 copy-number variants also indicates that severe obesity and being underweight could have mirror etiologies, possibly through contrasting effects on energy balance. The precise mechanisms underlining the phenotypes/disorders are currently unclear, but they are worth further exploring. Interestingly some genes have been shown to be involved in both obesity and CNS disorders, such as neurotrophin BDNF and neurotransmitter CART [21, 103, 104].
