Fragile X syndrome (FXS) is a genetic disorder characterized by mild-to-moderate intellectual disability. The average IQ in males with FXS is under 55, while about two thirds of affected females are intellectually disabled. Physical features may include a long and narrow face, large ears, flexible fingers, and large testicles. About a third of those affected have features of autism such as problems with social interactions and delayed speech. Hyperactivity is common, and seizures occur in about 10%. Males are usually more affected than females.This disorder and finding of Fragile X syndrome has an X-linked dominant inheritance. It is typically caused by an expansion of the CGG triplet repeat within the FMR1 (fragile X messenger ribonucleoprotein 1) gene on the X chromosome. This results in silencing (methylation) of this part of the gene and a deficiency of the resultant protein (FMRP), which is required for the normal development of connections between neurons. Diagnosis requires genetic testing to determine the number of CGG repeats in the FMR1 gene. Normally, there are between 5 and 40 repeats; fragile X syndrome occurs with more than 200. A premutation is said to be present when the gene has between 55 and 200 repeats; women with a premutation have an increased risk of having an affected child. Testing for premutation carriers may allow for genetic counseling.There is no cure. Early intervention is recommended, as it provides the most opportunity for developing a full range of skills. These interventions may include special education, speech therapy, physical therapy, or behavioral therapy.
OCD affects roughly 1–⁠2% of adults (somewhat more women than men), and under 3% of children and adolescents.A person with OCD knows that the symptoms are unreasonable and struggles against both the thoughts and the behavior. Their symptoms could be related to external events they fear (such as their home burning down because they forget to turn off the stove) or worry that they will behave inappropriately.It is not certain why some people have OCD, but behavioral, cognitive, genetic, and neurobiological factors may be involved. Risk factors include family history, being single (although that may result from the disorder), and higher socioeconomic class or not being in paid employment. Of those with OCD about 20% of people will overcome it, and symptoms will at least reduce over time for most people (a further 50%). Selective mutism
Selective mutism (SM) is a disorder in which a person who is normally capable of speech does not speak in specific situations or to specific people. Selective mutism usually co-exists with shyness or social anxiety. People with selective mutism stay silent even when the consequences of their silence include shame, social ostracism or even punishment. Selective mutism affects about 0.8% of people at some point in their life.Testing for selective mutism is important because doctors must determine if it is an issue associated with the childs hearing, movements associated with the jaw or tongue, and if the child can understand when others are speaking to them.