Written by Dr. Manny Alvarez
Ever since my son was diagnosed with autism 15 years ago, I have incorporated the testing of Fragile X in all my pregnant patients.
Even though the testing is not widely used in many obstetric practices around the country, many high-risk OB-GYNs feel it is important.
Fragile X is an inherited intellectual disability commonly seen in boys, which is caused by a change in the gene FMR1 on the X chromosome. The condition results in the failure to express FMRP – a protein needed for normal neural development.
According to the National Library of Medicine (NLM), the FMRI gene makes a protein needed for the brain to grow properly, and a defect in this gene makes the body produce either too little protein, or none at all.
Boys and girls can be afflicted by this condition – but because boys have one X chromosome, a single X is more likely to affect them, according to the NLM.
Although it’s important to test parents to see if they are carriers, children whose parents are not carriers can still be affected by the disorder. In fact, according to the NLM, Fragile X, developmental delays or intellectual disability may not be present in any of the family’s history.
Symptoms of fragile X often include mental disability, walking and language delays and hyperactivity – as well as certain physical characteristics such as an elongated face and large ears.
Other developmental delays to look for: delay in crawling or walking, hand clapping or biting and a tendency to avoid eye contact. Other physical signs may include flat feet, low-muscle tone, large forehead and soft skin. These problems can happen right at birth, or develop later on after puberty.
While Fragile X syndrome has similar symptoms to autism, it differs in that it has a very well described genetic underpinning.
Autism – or the autistic spectrum, which might include pervasive developmental disorders (PDD) or Asperger’s syndrome – is different from Fragile X syndrome.