OMIM 273750 (3-M syndrome) is a rare autosomal recessive condition caused by homozygous or compound heterozygous pathogenic variants in genes encoding cullin 7 (CUL7; type 1: MIM *609577), obscurin-like 1 (OBSL1; type 2: MIM *612921), or coiled-coil domain containing 8 (CCDC8; type 3: MIM *614205) (1). Here, CCDC8 is linked to 3-M syndrome.