Ring (15) chromosome.

Cytogenetic studies on lymphocytes from a girl aged 3 years and 10 months revealed revealed a ring chromosome 15. Several banding methods showed the r(15) chromosome not to have any apparent deletion of the long arm. The silver staining technique for nucleolar organizer regions showed an NOR positive region (band p12). In only a few cells was a chromosome 15 missing. The size of the r(15) was found to be constant. Comparison with 11 previous reported cases in the literature shows that the clinical manifestations in the different patients with ring chromosome 15 are constant although not clinically identifiable and it appears likely to attribute them to a significantly retarded intrauterine and postnatal growth instead of presumed deficiency in the long arm and mosaic configurations.