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Name: Corinne C.
Status: Other
Age: 30s
Location: N/A
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Date: N/A 


Question:
I have a triple X chromosone. I do not have Downs and the only real effects I seem to have is infertility. I have no eggs. I have tried to do IVF twice(with a donor) and have had no success. Do you know if someone with my condition can concieve with IFV and carry to term, or does this condition make it impossible. I've been told I am the only case in my state who has lived past 30. How common is my condition and what is the usual outcome of it?



Replies:
Triple X syndrome was initially found in individuals suffering from certain mental disabilities and has been discovered in about 1:1000 apparently normal females in routine examinations of newborns. Sterility is sometimes present and sometimes not with several Triple X women giving birth to chromosomally and physically normal children . It seems that there is, as is common in the world of genetics, a large clinical variation in the level of problems that the Triple X causes from nothing to quite a bit. I would check with a specialist in the field (which might be difficult to find) including any endocrinologists that specialize in this and also read whatever you can find. As in most of biology, these things are incompletely or poorly understood.

I also got this from the Merk Manual (on-line)

SEX CHROMOSOME ABNORMALITIES

Sex determination in humans is controlled by the X and the Y chromosomes. The female has two X chromosomes, and the male has one X plus one Y. The Y chromosome is among the smallest of the 46 chromosomes, and its major function seems to be related to male sex determination. In contrast, the X is one of the largest chromosomes and contains hundreds of genes, most of which have nothing to do with sex determination. Lyon hypothesis (X-inactivation): The normal female has two loci for every X-linked gene, as compared with the male's single locus. This would seem to produce a genetic "dosage" problem. However, according to the Lyon hypothesis, one of the two X chromosomes in each somatic cell of the female is genetically inactivated early in the life of the embryo. The Barr body, or sex chromatin mass within the nuclei of female somatic cells, represents the second inactivated X chromosome. The gene responsible for inactivating the genes of the X chromosome has been identified (XIST). Molecular genetic studies have demonstrated that not all genes on the second X chromosome are inactivated, but most are. In fact, no matter how many X chromosomes are present in the genome, all but one has most of the genes inactivated. X-inactivation has interesting clinical implications. For example, X chromosome abnormalities are relatively benign, compared with analogous autosomal abnormalities. Females with three X chromosomes are often normal physically and mentally and are fertile. In contrast, all the known autosomal trisomies have devastating effects. Similarly, the absence of one X chromosome, although it leads to a specific syndrome (Turner syndrome), is relatively benign; the absence of an autosome is invariably lethal.

Good luck.

Peter Faletra Ph.D.
Office of Science
Department of Energy



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