Host: Fragile X what does that mean?
Lakshmi Mehta: That's a separate condition which you have to distinguish between chromosome abnormalities, and problems within individual genes. Fragile X, the name came, because they have these large families where boys had mental retardation, and we knew that the gene had to lie on the X chromosome, because it seemed to be linked by women, and the effected boys had a certain picture that who is recognizable, but when they are studying these families in the old days, all they had available was chromosomes. So they use to do chromosomes on these boys, and one day in a lab in Australia, they actually were doing chromosome analysis at this, somewhat crude level that we have, and they noticed that every boy with mental retardation had a snap, had a little break in the X chromosome at its tip. So it got its name, they called it fragile X. The X seemed fragile at that point.
Host: Now that make sense.
Lakshmi Mehta: But it's only in ~90, I think it's was 1991,when we found out what exactly is going on at that spot where the X looked like it was broken, and what's going on there, is that there is an individual gene there, which you can't see under the microscope by a chromosome test, but you can do a separate test.
Host: So a fragile X you said boys, but can girls have Fragile X?
Lakshmi Mehta: They can, sometimes.
Host: It's kind of rare?
Lakshmi Mehta: It's much rare, about a third of girls who carry that genetic abnormality may actually has some degree of developmental problems, but usually minor than boys, and that's because, you know that girls have two X chromosomes, so one normal X can sometimes compensate.
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