title: Unbalanced reciprocal translocations at amniocentesis.
abstract: OBJECTIVE
  To present perinatal findings, modes of ascertainments, and modes of segregation in unbalanced reciprocal translocations detected at amniocentesis.
  
  
  METHODS
  Between January 1987 and July 2010, 40 cases with unbalanced reciprocal translocations were diagnosed by amniocentesis at Mackay Memorial Hospital, Taipei, Taiwan. The 40 cases originated from 29 families; 21 families with one case, 7 families with two cases, and 1 family with five cases.
  
  
  RESULTS
  Of 40 cases, 33 (82.5%) presented fetal ultrasound abnormalities and 7 (17.5%) presented no ultrasound abnormalities. Of 40 cases, 36 (90%) had a segregation mode of adjacent-1 2:2 segregation, 3 (7.5%) had a segregation mode of 3:1 segregation with tertiary trisomy, and 1 (2.5%) had a segregation mode of 3:1 segregation with tertiary monosomy. Of 29 families, 7 (24.1%) had de novo translocations and 22 (75.9%) had inherited translocations. In seven de novo cases, the main modes of ascertainments included abnormal ultrasound findings (n = 5) and advanced maternal age (n = 2). In 22 inherited families, the main modes of first ascertainment included abnormal ultrasound findings (n = 8), a previous aneuploid child (n = 8), advanced maternal age (n = 4), parental carrier status (n = 1), and abnormal maternal serum screening results (n = 1). Among 22 inherited families, 9 (40.9%) had a known parental carrier status, but 13 (59.1%) were unaware of parental carrier status at amniocentesis.
  
  
  CONCLUSIONS
  Unbalanced reciprocal translocations detected at amniocentesis are frequently associated with abnormal ultrasound findings. Prenatal diagnosis of an unbalanced translocation may incidentally detect a balanced translocation in the family. Prenatal diagnosis of fetal structural abnormalities should alert structural chromosome rearrangements and prompt cytogenetic analysis of the fetus and parents if necessary.
authors.affiliation: Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan. cpc_mmh@yahoo.com
authors.forename: Chih-Ping
authors.initials: CP
authors.lastname: Chen
authors.forename: Pei-Chen
authors.initials: PC
authors.lastname: Wu
authors.forename: Chen-Ju
authors.initials: CJ
authors.lastname: Lin
authors.forename: Schu-Rern
authors.initials: SR
authors.lastname: Chern
authors.forename: Fuu-Jen
authors.initials: FJ
authors.lastname: Tsai
authors.forename: Chen-Chi
authors.initials: CC
authors.lastname: Lee
authors.forename: Dai-Dyi
authors.initials: DD
authors.lastname: Town
authors.forename: Wen-Lin
authors.initials: WL
authors.lastname: Chen
authors.forename: Li-Feng
authors.initials: LF
authors.lastname: Chen
authors.forename: Meng-Shan
authors.initials: MS
authors.lastname: Lee
authors.forename: Chen-Wen
authors.initials: CW
authors.lastname: Pan
authors.forename: Wayseen
authors.initials: W
authors.lastname: Wang
mesh_terms: D000015:Abnormalities, Multiple / Q000000981:diagnostic imaging* / Q000235:genetics*; D000328:Adult; D000649:Amniocentesis; D002869:Chromosome Aberrations; D020090:Chromosome Segregation; D005260:Female; D006801:Humans; D011247:Pregnancy; D014178:Translocation, Genetic; D016216:Ultrasonography, Prenatal