Ring chromosome 21 transmitted from mother to daughter: its stability in a lymphoblastoid cell line.

A female infant with a high-pitched cry and hypertelorism but an otherwise normal facies was found to have the karyotype 46,XX,r(21)(p11.2q22.3). The r(21) was transmitted from the phenotypically normal mother. In both cases, the structure and behavior of the r(21) were rather stable in peripheral lymphocyte cultures. This stable nature of the r(21) was also confirmed in a lymphoblastoid cell line derived from the proband, where the normal-sized r(21) was persistent in most cells in prolonged culture for at least 5 months.