Fragile X Syndrome. Characteristics of Fragile X Syndrome

THE Fragile X Syndrome is a genetic disease linked to the X sex chromosome, being known as the most frequent cause of mental retardation. It is characterized by a CGG trinucleotide repeat of the X-chromosome FMR-1 gene. In a Fragile X patient, the repeat reaches over 200, so he is called a complete mutation carrier. In a normal individual, the trinucleotide repeat ranges from 6 to 55. When a person has repeats ranging from 55 to 200, we say he has a premutation.

The repetition of trinucleotides causes the FMRP protein, translated by the FMR 1 gene, not to be produced properly. As this protein is related to synaptic function and the growth of dendrites, its deficiency causes problems in normal brain functions.

The disease affects both men and women. However, in males, it is more severe. The incidence of the disease is 1 in every 4000 men and 1 in every 6000 women. The highest frequency in men is attributed to the fact that they have only one X chromosome. Since women have two X chromosomes, one healthy one makes up for the other.

the syndrome affects the intellectual development of the bearer and ranges from mild to profound mental impairment. In some cases, features of autism are noted. Furthermore, compromises the individual's behavior, who usually presents with attention deficit and hyperactivity. Another common symptom in people with the disease is the occurrence of seizures.

In addition to neurological and psychiatric variations, some variations in physical characteristics. Patients with the syndrome usually have a more elongated face, large ears, joint hyperextensibility, flat feet, and a high, high palate. These features are often associated with connective tissue involvement.

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In affected women, the occurrence of premature ovarian failure, which causes menopause even before the age of 40. In men, there are macrorchidism, that is, increase in the size of the testes.

O Diagnosis of Fragile X Syndrome it is done through exams that use molecular biology techniques to study the patient's DNA. Gene analysis is usually done using the PCR technique and Southern blotting. The karyotype test was used for a long time to diagnose the Syndrome, however, it is a procedure that can generate a false negative and is therefore not recommended.

After the diagnosis of the syndrome, it is important to start the treatment, which does not lead to cure, but improves quality of life. The treatment has as main objectives to socialize the carrier and improve their learning. For the therapy to work properly, it is essential that the work be performed by different professionals, such as neurologists and speech therapists.

Attention!In cases of diagnosis of the disease, it is essential that a genetic counseling.

By Ma. Vanessa dos Santos

Would you like to reference this text in a school or academic work? Look:

SANTOS, Vanessa Sardinha dos. "Fragile X Syndrome"; Brazil School. Available in: https://brasilescola.uol.com.br/biologia/sindrome-x-fragil.htm. Accessed on June 28, 2021.