Social, communicational, and behavioral deficits associated with ring X turner syndrome.

We describe the cognitive and behavioral characteristics of five individuals with a ring X chromosome. All subjects had a small active (early replicating) ring X chromosome. The X inactive specific transcript (XIST) locus was confirmed by fluorescent in situ hybridisation (FISH) to be present in all ring X chromosomes. Mental retardation was present in four individuals. All patients with or without mental retardation had a characteristic profile of aggression toward self and others, episodes of screaming, attentional problems, and impulsiveness. Autistic-like features were also present in all individuals and included limited communication, obsessive compulsive behavior, and social difficulties. In some cases the obsessive behavior was extreme and incapacitating. This characteristic behavioral profile may aid the diagnosis and future understanding of ring X.