Prenatal diagnosis of mosaic distal 5p deletion and review of the literature

Objectives To present the prenatal diagnosis of mosaic distal 5p deletion and a review of the literature. Clinical subject and methods A 37-year-old woman, gravida 2, para 1, underwent genetic amniocentesis at 17 weeks' gestation because of advanced maternal age. Cytogenetic analysis of the cultured amniocytes revealed mosaicism for a distal 5p deletion, mos 46,XX,del(5)(p15.1)/46,XX (23 colonies/23 colonies). Repeat amniocentesis showed a consistent karyotype of mos 46,XX,de1(5)(p15.1)/46,XX (12 colonies/15 colonies). The parental karyotypes were normal. Prenatal ultrasound demonstrated microcephaly and cerebellar hypoplasia. The pregnancy was terminated at 21 weeks' gestation. Postnatally, the fetus displayed microcephaly, a triangular face, hypertelorism, epicanthic folds, down-slanting palpebra] fissures, low-set ears, and micrognathia. A karyotype of mos 46,XX,de1(5)(p15.1)/46,XX was found in the cord blood, liver, lungs, and skin, whereas the placenta had a different karyotype of mos 46,XX,dup(5)(qter-->p15.3::p15.3-->p10)/46,XX, and the karyotype of the amnion was mos 46,XX,del(5)(p15.1)/46,XX,dup(5)(qter-->p15.3::p15.3-->p10)/46,XX,trp(5)(qter-->p15.3::p15.3-->p10::p10 -->p15.3)/46,XX. The deletion, duplication, and triplication of the terminal region of the short arm of chromosome 5 were confirmed by the studies of fluorescence in situ hybridization. Conclusion The cri-du-chat syndrome can be identified prenatally because of advanced maternal age, familial cri-du-chat syndrome, parental balanced translocations involving chromosome 5, sonographically detected fetal structural abnormalities, and/or an abnormal maternal serum test. Fetuses with the mosaic distal 5p deletion may be associated with the sonographic findings of microcephaly and cerebellar hypoplasia, and fetoplacental and fetoamnionic chromosomal discrepancies. Copyright (C) 2004 John Wiley Sons, Ltd.