A ring chromosome in man.

THE known chromosomal abnormalities in man comprise mainly whole chromosome and segmental monosomy and trisomy. Ring chromosomes have been described in tumour stem lines1,2 and in normal tissues following irradiation3. Recently a ring X-chromosome has been reported in a female with gonadal dysgenesis4. A self-perpetuating ring chromosome is now described in a mentally and physically retarded but pubertal male. A full clinical description of the case is being published elsewhere5.