Five new subjects with ring chromosome 22

Abstract

Ring chromosome 22, a rare cytogenetic finding, was first described by Weleber et al. in 1968. Since then approximately 50 patients have been reported in the medical literature. We describe five previously unreported subjects with ring chromosome 22 syndrome, summarize the clinical findings of reported patients from the literature and discuss the involvement of the ring chromosome and clinical outcome. Our subjects demonstrated the prominent features of this syndrome including mental retardation, hypotonia, motor delay, lack of speech, full eyebrows, and large ears. In addition, two of our subjects had central nervous system malformations and regression. The lack of consistent physical abnormalities in our subjects further supports no consistent phenotype manifestations in this cytogenetic syndrome. The variable clinical manifestations seen in ring chromosome 22 subjects may be associated with loss of chromosome 22 sequences near the telomere or attributed to the genetic background of each subject. Similarly, recessive alleles unmasked by the deletion could also contribute to the phenotype.

Fig. 1.

Frontal view of subject 1 at 12 years of age.

Fig. 2.

Clinical findings in 58 patients with ring chromosome 22. The summary of clinical findings is given for 58 patients (53 from the literature and our 5 subjects) with ring chromosome 22. Not all subjects reported in the literature included sufficient information to determine if the finding was present or absent. Therefore, the percentage listed for each finding represents those subjects in which pertinent information was available to determine the presence or absence of the particular finding [e.g. 25 of 38 subjects (66%) had large ears]. Thirty-six subjects were reviewed by Severien et al. (2) An additional 17 subjects have been reported [Taalman et al. (13), Naritomi et al. (14), Watanabe et al. (15), Christodoulon et al. (16), Ritter et al. (17), Tommerup et al. (18), Petrella et al. (7), Coulter-Mackie et al. (19), Joyce et al. (20), Sovner etal. (3), Kehrer-Sawatzki et al. (21), Rubio et al. (22), Assumpcao (23), Gibbons et al. (24), MacLean et al. (4), Arnold et al. (9), De Mas et al. (25)]