Fragile (X) expression: Relationship to the cell cycle

✍ Scribed by E. S. Cantú; Patricia A. Jacobs

• Publisher: Springer
• Year: 1984
• Tongue: English
• Weight: 565 KB
• Volume: 67
• Category: Article
• ISSN: 0340-6717
• DOI: 10.1007/bf00270565

✦ Synopsis

The fragile (X) chromosome demonstrable in individuals with one type of X-linked mental retardation is seldom, if ever, seen in more than 50% of cells of affected individuals. We have devised a model to explain this apparent 50% maximum, one essential feature of which is that the fragile (X) will not be seen in cells in their first division in thymidine-depleted media. The validity of our model was tested on lymphoblastoid cell lines from affected males by treating the cells with fluorodeoxyuridine (FUdR) to induce the marker and/or bromodeoxyuridine (BrdU) to determine the cell cycle. We have evidence that the fragile (X) is present in cells in the first and subsequent cell divisions in thymidine-depleted media. In light of these observations our model is not valid and the 50% expression of the fragile site at Xq(28) and other unusual properties of this region of the X chromosome remain unexplained.