Ring Chromosome 22, Mood Disorder and Sodium Valproate (A Case Report)

Ring chromosome, also known as ring 22, or r (22), was first reported by Weleber and confirmed by Magenis (Weleber et al., 1968). So far, only a few cases have been described. Its incidence is considered to be one per million in the UK. It arises from terminal breaks on both arms of chromosome 22 followed by fusion. Although familial cases have been described, it is mainly considered to be caused by spontaneous or de novo errors very early in the development of the embryo (Battini et al., 2004). The physical phenotype is not very distinct with mild and variable dysmorphic features. Cognitive aspects are of moderate to severe learning disability. Behavioural aspects are absence of speech and autistic behaviour. Bipolar affective disorder has been described in ring chromosome 22 (Sovner et al., 1996; MacLean et al., 2000).