Fragile X Genetic Disorder

Cindy is an expectant mother who is eight weeks pregnant with her first child. She is having a genetic test because there is a history of learning disabilities and mental impairment in her family. Based on her family history, there is a possibility that she is a carrier for Fragile X, a genetic disorder that occurs when a person’s X chromosome(s) contains greater than 200 repeats of the CGG base pair sequence. Symptoms in infants include a delay in crawling, walking, or twisting, frequent hand clapping or biting, hyperactive or impulsive behavior, mental impairments, speech delay, and the tendency to avoid eye contact. In children and adults, physical symptoms include flat feet, flexible joints, low muscle tone, large body size, large forehead and ears, a prominent jaw, a long face, and
However, she will be a carrier of the full mutation and her offspring will be susceptible to Fragile X. Because some of the woman’s cells have Fragile X and some don’t, she is known as a mosaic. Males only have one X chromosome, which means that if there is a mutation on that chromosome, there is no other X for the cells to fall back on and the male will have the full disorder. Men who are carriers cannot pass the gene onto their sons because they give their sons the Y chromosome, meaning the mutation on the X will not be inherited. Alternately, the man will pass the premutation onto all of his daughters because they must receive his one mutated X chromosome in order to be female. Later in life, some female carriers may experience Fragile X Associated Primary Ovarian Insufficiency, which is abnormal function of the ovaries, which can lead to infertility and early menopause. Some male carriers may experience Fragile X Associated Tremors and Ataxia Syndrome, which affects balance and memory and can also cause