The use of sequential silver and quinacrine staining to determine the parental origin and breakpoints of a ring‐22 human chromosome

Abstract

We delineated a G‐ring syndrome in 1968 and suggested it was due to a ring‐22 (Weleber et al. 1969). We confirmed in 1972 that the ring was derived from chromosome 22 (Magenis et al. 1973). The present report constitutes a new case of the ring‐22 syndrome with clinical findings virtually identical to those we described earlier. By sequential staining techniques with silver and quinacrine, it was possible to determine the parental origin of the ring (maternal) and to estimate the breakpoints in the chromosome 22 (22p12 and 22q13) leading to the ring configuration. The clinical abnormalities are due to terminal deletion of 22q distal to the breakpoint in band 22q13. The silver technique, especially in sequence with other stains, provides new and useful data concerning the origin and precise cytology of this, one of the tiniest rings known in humans.