Mosaicism 45,X/46,X, t dic(Xp:Xp) in a girl with short stature

An eight-year-old girl with marked short stature and no apparent stigmata of Turner syndrome was investigated. Clinical features include bilateral epicanthic folds, frontal bossing, prominent ears and normal intelligence. Ultrasound scanning revealed an apparently normal vagina, streak ovaries and no uterus. Bone age was normal. Karyotype analysis of peripheral blood lymphocytes showed mos 45,X/46,X tdic(Xp:Xp) in the ratio 66:34, respectively. In addition, three cells with different abnormal X chromosomes were present which possibly originated from a 46,XX clone. Replication of the duplicated X chromosome was consistently late and symmetrical. Buccal smear confirmation of the karyotype showed Barr body negative in 90% and large or bipartite in 10% of the cells. Karyotypes of the parents were normal. The clinical manifestations in cases of Xp deletion due to terminal rearrangement associated with or without a 45,X cell line are discussed.