16p11.2 deletion syndrome is a rare genetic condition caused by microdeletion on the short arm of chromosome 16.
[3][4] The most commonly observed features of 16p11.2 deletion syndrome are global developmental delay and psychiatric or behavioral issues, though severity varies significantly.
Hyporeflexia, gait abnormalities, and truncal or symmetric limb hypotonia were observed in at least 15% of individuals in a cohort of 136 16p11.2 deletion carriers.
16p11.2 deletion syndrome strongly predisposes individuals to increased body mass index (BMI) and obesity beginning in childhood.
[7] Obesity and related comorbidities such as insulin resistance or type 2 diabetes comprise the majority of medical challenges for adults with 16p11.2 deletion syndrome.
[8] 16p11.2 deletion syndrome is caused by a heterozygous microdeletion of ~600 kilobases between the recurrent breakpoint regions BP4 and BP5 on the short arm of chromosome 16.
Due to increased risk of obesity associated with the syndrome, psychiatric medications associated with weight gain are not recommended.