Fragile X Syndrome
Fragile X is a genetic syndrome characterised by mental retardation, an elongated face, large protruding ears, and large testicles (in men).
They tend to be shy, avoid eye contact, and have difficulties reading facial expressions. They often display stereotypic movements such as hand flapping.
Fragile X is the most common inherited cause of learning disability.
The speech of affected individuals of often abnormal. Of note are abnormalities of fluency (flow). Such speech is often referred to as cluttered.
It is an X-linked dominant disorder caused by the amplification of a CGG repeat in the 5 untranslated region of the fragile X mental retardation 1 gene (FMR1). These CGG repeats disrupt synthesis of the fragile X protein (FMRP) known to be essential for brain function and growth. The gene is located at Xq27. As with other trinucleotide repeat disorders (Huntington's, myotonic dystrophy, Friedreich's ataxia, and spinocerebellar ataxia) the greater number of repeats the more severe the condition.
The fragile X phenotype typically involves a variety of psychiatric symptoms, including features of autism, attention deficit/hyperactivity disorder, anxiety, and aggression.
Females as well as males are affected. This is through the process of X-inactivation, where one X in each female cell inactivates itself. Males are more severely affected because they have only one X chromosome.
It has a prevalence estimate of 1/3600-4000.
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They tend to be shy, avoid eye contact, and have difficulties reading facial expressions. They often display stereotypic movements such as hand flapping.
Fragile X is the most common inherited cause of learning disability.
The speech of affected individuals of often abnormal. Of note are abnormalities of fluency (flow). Such speech is often referred to as cluttered.
It is an X-linked dominant disorder caused by the amplification of a CGG repeat in the 5 untranslated region of the fragile X mental retardation 1 gene (FMR1). These CGG repeats disrupt synthesis of the fragile X protein (FMRP) known to be essential for brain function and growth. The gene is located at Xq27. As with other trinucleotide repeat disorders (Huntington's, myotonic dystrophy, Friedreich's ataxia, and spinocerebellar ataxia) the greater number of repeats the more severe the condition.
The fragile X phenotype typically involves a variety of psychiatric symptoms, including features of autism, attention deficit/hyperactivity disorder, anxiety, and aggression.
Females as well as males are affected. This is through the process of X-inactivation, where one X in each female cell inactivates itself. Males are more severely affected because they have only one X chromosome.
It has a prevalence estimate of 1/3600-4000.
