Transmission of ring 14 chromosome from mother to two sons

We report on a family with transmission of a ring chromosome 14 from an affected mother to her 2 sons. The mother was mosaic, 46,XX,r(14)/45,XX,t(14q21q). Both of her sons, affected by seizures and mental retardation, have the karyotype 46,XY,r(14). In considering the association of translocation 14:21 in the mother with ring 14, we postulate that either the ring chromosome was formed first and then opened with translocation of the partially deleted chromosome 14 to chromosome 21, or the 14:21 translocation was present first, then the chromosomes 14 and 21 broke apart, and the partially deleted 14 formed the ring. The published literature of cases of ring 14 is reviewed.