Mutations in three genes are known to cause 3-M syndrome: CUL7 (type 1; OMIM #273750), OBSL1 (type 2; OMIM #612921), and CCDC8 (type 3; OMIM #614205), with roughly 65% of 3-M syndrome mutations described in CUL7, and 30% in OBSL1. Functional analysis suggests that proteins encoded by these three genes interact in a pathway involved in insulin-like growth factor signalling [2]. This evidence concerns the gene CUL7 and multiple congenital anomalies-hypotonia-seizures syndrome 3.