Which of the following cytogenetic results listed below indicate that the child in question has Down syndrome?
E. 46,XX.ish del(21)(q22.3q22.3)(D21S65-)
Which of the following karyotypes, if observed in an embryo, is least likely to survive to birth?
E. mos 47,XXX/46,XX
Regarding X chromosomes, which of the following statements is false?
A. In normal females, the inactivated X chromosome has most, but not all of its gene expression extinguished as a result of X inactivation
B. Klinefelter syndrome is due to unbalanced gene expression derived from the presence of an extra X chromosome in males
C. Severe Turner syndrome (i.e. with severe intellectual impairments) due to a very small ring X chromosome, notated 46,Xr(X), is caused by lack of expression of the XIST gene, resulting in functional disomy for genes present on r(X)
D. Barr bodies are only seen in cells with 2 or more X chromosomes, and not, for example, in cells from normal males
E. The TSIX gene is expressed from the inactivated X chromosome in females
9th EditionCain, Jackson, Minorsky, Reece, Urry, Wasserman
Joseph S. Levine, Kenneth R. Miller
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