3‐M syndrome is a rare autosomal recessive disorder characterized by primordial growth retardation, large head circumference, characteristic facial features, and mild skeletal changes, which is associated with the exclusive variants in three genes, namely CUL7, OBSL1, and CCDC8. Only a few 3‐M syndrome patients have been reported in Chinese population. Here, CUL7 is linked to multiple congenital anomalies-hypotonia-seizures syndrome 3.