title: Isochromosome Yp and jumping translocation of Yq resulting in five cell lines in an infertile male: a case report and review of the literature.
abstract: BACKGROUND
  Jumping translocations are a rare type of mosaicism in which the same portion of one donor chromosome is translocated to several recipient chromosomes. Constitutional forms of jumping translocations are rare, and the 48 cases reported to date have been associated with both normal and abnormal phenotypes. Concurrence of isochromosome (i) of one arm and translocation of the other is also rare, with seven reported cases. We describe a unique case involving concurrence of i(Yp) and a jumping translocation of Yq to the telomere of chromosomes 12q and 17q, which resulted in five cell lines.
  
  
  METHODS
  The patient, an otherwise healthy 35-year-old man, was referred for cytogenetic studies because of absolute azoospermia. He had elevated levels of follicle stimulating hormone and luteinizing hormone, consistent with abnormal spermatogenesis, and decreased levels of free testosterone and inhibin B. G-banded chromosome analysis revealed a mosaic male karyotype involving five abnormal cell lines. One of the cell lines showed loss of chromosome Y and presence of i(Yp) as the sole abnormality. Three cell lines exhibited jumping translocation: two involved 17qter, and the other involved 12qter as the recipient and Yq as the common donor chromosome. One of the cell lines with der(17) additionally showed i(Yp). The other der(17) and der(12) cell lines had a missing Y chromosome. All five cell lines were confirmed by FISH. Subtelomric FISH study demonstrated no loss of chromosome material from the recipient chromosomes at the translocation junctions.
  
  
  CONCLUSIONS
  We postulate that a postzygotic pericentromeric break of the Y chromosome led to formation of isochromosome Yp, whereas Yq formed a jumping translocation through recombination between its internal telomere repeats and telomeric repeats of recipient chromosomes. This in turn led to either pairing or an exchange at the complimentary sequences. Such translocation junctions appear to be unstable and to result in a jumping translocation. Cryptic deletion or disruption of AZF (azoospermic factor) genes at Yq11 during translocation or defective pairing of X and Y chromosomes during meiosis, with abnormal sex vesicle formation and consequent spermatogenetic arrest, might be the main cause of the azoospermia in our patient.
authors.affiliation: Cytogenetics Department, Quest Diagnostics Nichols Institute, 33608 Ortega Highway, San Juan Capistrano, CA 92690, USA.
authors.forename: Morteza
authors.initials: M
authors.lastname: Hemmat
authors.affiliation: Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA.
authors.forename: Omid
authors.initials: O
authors.lastname: Hemmat
authors.affiliation: Cytogenetics Department, Quest Diagnostics Nichols Institute, 33608 Ortega Highway, San Juan Capistrano, CA 92690, USA.
authors.forename: Fatih Z
authors.initials: FZ
authors.lastname: Boyar
references.citation: J Med Genet. 1983 Oct;20(5):394-6
references.pmid: 6644772
references.citation: Am J Hum Genet. 1992 May;50(5):914-23
references.pmid: 1570843
references.citation: Genet Couns. 2010;21(4):397-404
references.pmid: 21290969
references.citation: Hum Genet. 1979 Sep;50(3):237-40
references.pmid: 489006
references.citation: Hum Genet. 1996 Sep;98(3):291-6
references.pmid: 8707296
references.citation: Chromosoma. 1990 Apr;99(1):3-10
references.pmid: 2340757
references.citation: Blood. 1998 Mar 1;91(5):1732-41
references.pmid: 9473240
references.citation: J Med Genet. 1997 May;34(5):395-9
references.pmid: 9152837
references.citation: Hum Reprod. 1996 Dec;11 Suppl 4:1-24; discussion 25-6
references.pmid: 9147109
references.citation: Genes Chromosomes Cancer. 2007 Aug;46(8):717-23
references.pmid: 17444494
references.citation: Hum Reprod. 2002 Mar;17(3):564-9
references.pmid: 11870104
references.citation: Hum Mol Genet. 1996 Jul;5(7):933-43
references.pmid: 8817327
references.citation: Cancer Genet Cytogenet. 1997 Oct 1;98(1):20-7
references.pmid: 9309114
references.citation: Ann Genet. 1976 Jun;19(2):127
references.pmid: 1085601
references.citation: Clin Genet. 1998 May;53(5):415-20
references.pmid: 9660064
references.citation: Clin Genet. 1999 Feb;55(2):122-6
references.pmid: 10189090
references.citation: Hum Genet. 1979 Nov;52(2):175-8
references.pmid: 511173
references.citation: Am J Med Genet A. 2004 Aug 30;129A(2):120-3
references.pmid: 15316974
references.citation: J Urol. 1989 Jul;142(1):62-5
references.pmid: 2499695
references.citation: Am J Med Genet. 1994 Nov 1;53(2):108-40
references.pmid: 7856637
references.citation: Hum Genet. 1998 Jan;102(1):98-102
references.pmid: 9490306
references.citation: Hum Genet. 2000 Sep;107(3):268-75
references.pmid: 11071389
references.citation: Clin Genet. 1987 Jun;31(6):393-8
references.pmid: 3621643
references.citation: Am J Med Genet. 1998 Aug 27;79(1):35-7
references.pmid: 9738866
references.citation: Hum Genet. 1979 Feb 15;46(3):271-8
references.pmid: 437770
references.citation: J Med Genet. 1993 Nov;30(11):926-31
references.pmid: 8301647
references.citation: Am J Med Genet. 1994 Aug 15;52(2):214-7
references.pmid: 7802011
references.citation: Hum Reprod. 1991 Feb;6(2):245-50
references.pmid: 2056021
references.citation: Hum Genet. 1978 May 16;42(1):93-7
references.pmid: 649175
references.citation: Ann Genet. 1998;41(1):22-6
references.pmid: 9599647
references.citation: Cytogenet Cell Genet. 1982;33(4):312-8
references.pmid: 7172762
references.citation: Clin Genet. 1996 Mar;49(3):156-9
references.pmid: 8737982
references.citation: Am J Hum Genet. 1994 Feb;54(2):290-302
references.pmid: 8304346
references.citation: Hum Reprod. 2005 Aug;20(8):2168-72
references.pmid: 15845593
references.citation: Am J Med Genet A. 2010 Nov;152A(11):2924-36
references.pmid: 20979197
references.citation: Trends Genet. 1989 Oct;5(10):326-31
references.pmid: 2692239
references.citation: Hum Genet. 1997 Jun;99(6):735-7
references.pmid: 9187665
references.citation: Ann Genet. 1979;22(4):210-3
references.pmid: 317782
references.citation: Cell. 1999 May 14;97(4):419-22
references.pmid: 10338204
references.citation: Am J Med Genet. 1993 Jul 1;46(6):715-20
references.pmid: 8362916