Fragile X Syndrome is a dominant X- linked syndrome, meaning it affects both men and women. Since men only have one x chromosome, it effects them more frequently and with more severity. In inheritance, the father passes on Fragile X only to the daughters since sons will recieve a Y chromosome from him. If the mother has Fragile X or acts as a carrier for it, there is a 50% chance her children will be affected by it.
The Fragile X mutation was discovered in 1943 by two scientists, Bell and Martin. The disease was originally named after them, but then was renamed after it was found to a sex-linked condition with a "fragile" site on the X chromorosome. The mutation that causes Fragile X is a CGG repeat on the X that extends more than normal. Normally, it repeats between 6 and 55 times. Anything over 55 repeats is considered Fragile X.
About 50% of women with Fragile X do not show any symptoms (long face, large ears, and flat feet). Also men and women who have between 55 and 200 CGG repeats have what is called "pre-mutation" Fragile X. Pre-mutation is incomplete Fragile X but can cause multiple issues like ovarian failure and Tremor Ataxia Syndrome. If someone has 200 or more CGG repeats, they have complete Fragile X. The greater the number of repeats, the greater the severity of the effects.
Comments
Spacing
Paragraph = 1 paragraph; these are 3 mini-paragraphs (that are all strong!) but a paragraph is put together.
Also I'd suggest not to mention what Fragile X is before you define it, otherwise this can confuse readers.
scientists
The first time you introduce a person you should list their full name.
Comment
To strengthen the flow of your ideas, I would re-order the paragraphs. Perhaps a more ideal order would start with paragraph 2, then 1, then paragraph 3 (switch the first two). Broader to more specific