Fragile X Syndrome (FXS), described by Martin & Bell, wherefrom comes its another name Martin Bell Syndrome refers to an X-linked genetic condition that most frequently causes Intellectual Disability and other neurological and psychiatric disorders. It accounts for about one-half of cases of X-linked mental retardation and is the most common cause of mental impairment after trisomy 21. About a third of these children have features of autism and delayed speech that is present from an early age. Hyperactivity and seizures are also common. Males are usually more affected than females. Life expectancy is lower than in the general population. FXS can be passed down from parents to children through genes.
Features suggesting the presence of FXS are:
Developmental delays (not sitting, walking, or talking at the same time period as other children of the same age);
Learning disabilities (trouble learning new skills); and
Social and behaviour problems (such as not making eye contact, anxiety, trouble paying attention, hand flapping, acting and speaking without thinking, and being very active).
Some children with fragile X might have distinct physical features like a large head, a long, narrow face, large ears, a large forehead and chin, loose joints, flat feet, enlarged testicles (after puberty).
The epidemiology of Fragile X syndrome is found to be occurring about 1 in 4000 males and 1 in 8000 females. Female carrier is estimated to be as high as 1 in 130 to 250 population, and the incidence of male carriers is about 1 in 250 to 800 population.
Cause & Detection
Fragile X Syndrome is caused by changes in the gene called the fragile X mental retardation 1 (FMR1) gene which makes a protein called fragile X mental retardation protein (FMRP). FMRP is needed for normal brain development that is missing in people with FXS. The FMR1 gene is on the X chromosome. Because the FXS mutation is an expanding mutation that can become bigger when passed on to the next generation, diagnosed individuals may lack a recognized family history of FXS. However, a family history of other fragile X-associated disorders, such as tremors and early menopause, can be an indication that a child with unexplained developmental delay, intellectual disability or autism has these features because of unrecognized FXS in the family.
A specific test called the “FMR1 DNA Test for Fragile X” can be administered to test whether a child has FXS or not.
Treatment
Even though there is no cure for FXS there are treatment services that can help people learn important skills. Management includes speech therapy, behavioural therapy, occupational therapy, and special education. Early intervention is particularly important that helps improving a child’s development. Individuals with FXS in their family should consider genetic counselling to assess the likelihood of having a child that is affected. Medications used for symptom-based treatment aim to minimize some of the behavioural and mental health challenges associated with FXS. Stimulants may target hyperactivity, impulsivity, and attention issues, antidepressants may treat anxiety, obsessive-compulsive behaviours, and mood disorders, and antipsychotics are an option if self-injurious or aggressive behaviours are present, while anticonvulsants help to control seizures.
- Shivangi Banerjee