Fragile X syndrome is a genetic condition that involves complications in the part of X chromosome. It is the commonest form of inherited intellectual disability (mental retardation) in boys.
Causes, incidence, and risk factors
Fragile X syndrome is caused by a change in a gene called FMR1. A small part of the gene code is repeated on a fragile area of the X chromosome. The more repeats, the more likely there is to be a problem.
The FMR1 gene makes a protein needed for your brain to grow properly. A defect in the gene makes your body produce too little of the protein, or none at all.
Boys and girls can both be affected, but because boys have only one X chromosome, a single fragile X is likely to affect them more severely. You can have Fragile X syndrome even if your parents do not have it. Usually females are the carriers of this Fragile X chromosome.
Symptoms
Behavior symptoms associated with fragile X syndrome includes
- Delay in crawling, walking, or twisting
- Hand clapping or hand biting
- Hyperactive or impulsive behavior
- Mental retardation
- Speech and language delay
- Tendency to avoid eye contact
Physical signs may include
- Flat feet
- Flexible joints and low muscle tone
- Large body size
- Large forehead or ears with a prominent jaw
- Long face
- Soft skin
Some of these problems are present at birth, while others may not develop until after puberty.
Signs and Symptoms
There are very few outward signs of Fragile X syndrome in babies. Some signs may include
- Large head circumference in babies
- Mental retardation
- Large testicles after the start of puberty
- Subtle differences in face features
