Cases with typical 16p11.2 BP4-BP5 deletion or distal 16p11.2 BP2-BP3 deletion have an increased risk of developing obesity and macrocephaly, while cases with a typical 16p11.2 BP4-BP5 duplication or a distal 16p11.2 BP2-BP3 duplication more often present with underweight and microcephaly [10, 11]. Here, IGFBP2 is linked to obesity due to melanocortin 4 receptor deficiency.