Fragile X syndrome (also known as Martin and Bell Syndrome) is the second leading cause of intellectual disability in children (after Down’s syndrome): it affects 1 in 5,000 boys and 1 in 9,000 girls. The name of this syndrome is related to the fragility of the X chromosome observed in patients. It can be reflected in a more or less marked way by behavioral disorders, language, mood, learning difficulties, a difficulty in managing his emotions… Behavioral characteristics similar, sometimes, to those of autistic children, especially in boys. In girls, intellectual and behavioral disorders are generally more discreet: they mainly suffer from emotional and learning disorders. The total number of people carrying the genetic anomaly, with or without manifestations, is around 10,000 in France.
Fragile X syndrome is caused by an abnormality in part of the DNA located in and near the FMR1 gene on the X chromosome. The X chromosome is one of the two chromosomes that determine the sex of an individual
: men have one X chromosome and one Y chromosome, while women have two X chromosomes. In fragile X syndrome, a sequence of three bases (CGG triplet) is repeated an abnormal number of times. in part of the DNA of the X chromosome, resulting in the lack of production of a protein (FMRP) necessary for proper brain function.
In boys as in girls, the physical signs are discreet: narrow and elongated face, prominent ears and forehead, hyperlaxity of the fingers and flat feet are the main signs of this hereditary disease. These physical characteristics being discreet or completely absent, they do not allow a diagnosis to be made.
Often the first manifestation of the disease is a delay in the development of the child, sometimes detected at the time of the acquisition of walking, but more often at the time of language development.
The diagnosis is mainly based on the molecular screening of any child with an intellectual deficit or autism.
On the occasion of European Fragile X Day, the film Mission to Lars is being released in a few theaters in France. This film tells the true story of Tom Spicer, who suffers from fragile x syndrome. Tom’s only dream was to meet Lars Ulrich, the drummer for the band Metallica. His brother and sister will try to make his dream come true but the trials to reach the backstage of the group will make the mission very difficult.
