Ring chromosome 9 syndrome is an autosomal anomaly characterized by variable clinical features, most commonly including developmental delay, some degree of intellectual disability, facial dysmorphism, microcephaly, congenital heart anomalies, and variable genital, limb and skeletal anomalies.

Subnormal intellectual functioning which originates during the developmental period. Intellectual disability, previously referred to as mental retardation, has been defined as an IQ score below 70.