Human Genetics

, Volume 76, Issue 1, pp 1–4 | Cite as

What causes the abnormal phenotype in a 49,XXXXY male?

  • Gloria E. Sarto
  • Priscila G. Otto
  • Evelyn M. Kuhn
  • Eeva Therman
Original Investigations


The chromosome replication pattern of a man with 49,XXXXY was analyzed using 3H-thymidine and autoradiography as well as BrdU and acridine orange. The former technique showed a highly irregular replication pattern; the latter revealed one early replicating X chromosome, and the other three more or less asynchronously replicating. Two hypotheses seem to explain best the abnormal phenotype of males with an XXXXY sex chromosome constitution: (1) The number of the always active regions (tip of Xp) and of the possibly always active regions (the Q-dark regions on both sides of the centromere) is increased from one to four. (2) The replication pattern of the late-replicating X chromosomes is highly asynchronous, which might affect the phenotype. The possibility that more than one X chromosome might remain active in some cells, an even more abnormal and obviously deleterious situation, is still open.


Internal Medicine Active Region Metabolic Disease Acridine Acridine Orange 
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Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • Gloria E. Sarto
    • 1
  • Priscila G. Otto
    • 2
  • Evelyn M. Kuhn
    • 3
  • Eeva Therman
    • 4
  1. 1.Department of Obstetrics and GynecologyUniversity of New Mexico, School of MedicineAlbuquerqueUSA
  2. 2.Laboratorio de Genetica Humana, Departmento de Biologia, Institute de BiocienciasUniversidade de Sao PauloS.P.Brazil
  3. 3.Department of Obstetrics and Gynecology, Mount Sinai Medical CenterUniversity of Wisconsin-MilwaukeeMilwaukeeUSA
  4. 4.Department of Medical GeneticsUniversity of WisconsinMadisonUSA

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