Fragile X syndrome (FXS) is an inherited condition associated with a range of developmental difficulties including learning disabilities and cognitive impairment. In addition, individuals with FXS may experience anxiety, hyperactive behaviour, attention deficit disorder (ADD), features of autism spectrum disorders, seizures, fertility problems (female) and social interaction. Usually, males are more severely affected than females. As children with FXS mature, characteristic physical features (such as long, narrow face, large ears, prominent jaw and forehead, unusually flexible fingers, flat feet and enlarged testicles) may become more apparent (particularly in males).
FXS is caused by a mutation in the gene that gives the instruction for a protein (which helps regulate the production of other proteins and plays a role in the development of synapses). The deficiency of this protein upsets the nervous systems and results in the symptoms of FXS. Large mutations to the gene cause FXS. However, some people have small mutations to this gene and they are described as being carriers, or having a premutation. Some carriers may develop (gender-dependent) cognitive or social/emotional symptoms of one of the two Fragile X-associated Disorders: Fragile X Tremor Associated Ataxia (FXTAS) and Fragile X-Associated Primary Ovarian Insufficiency (FXPOI). FXTAS is a neurological condition which onsets usually in males over the age of 50 and some women may experience premature ovarian failure (FXPOI). Therefore, Fragile X consists of a family of three genetic conditions.