Martin-Bell Syndrome: The Weakness of the X Chromosome

The fragile X syndrome, also known as Martin-Bell syndrome, is a hereditary disorder associated with the vulnerability of the X chromosome. This condition is the second most common cause of congenital intellectual disability, following Down syndrome. Among affected individuals, the prevalence of the disorder is more common in boys, but it can also manifest in girls, albeit in a different form.

Research has provided a precise understanding of the genetic background of the disorder. A repeating amino acid sequence on the X chromosome typically occurs a maximum of 31 times. However, if this repetition exceeds a critical number, the chromosome becomes unstable, leading to the development of fragile X syndrome.

The disorder can present various symptoms that can be quickly noticed after birth. Affected newborns have distinctive facial features, such as an elongated head shape, large protruding ears, and thick lips. Additionally, flat foot arches, enlarged testicles, as well as hypotonic muscles and loose joints may also be observed. Due to the weakness of connective tissues, these children are more prone to hernias and frequently experience infections. Abnormalities in heart valve function can also be observed, requiring medical supervision.

The disease is not only associated with physical symptoms. As children grow, cognitive and behavioral disorders also become evident. They often experience delays in speech development and may later face learning difficulties. Affected children may exhibit unusual behaviors, perform repetitive movements, and struggle to form social connections. Their academic performance is also weaker, particularly in reading and writing, and their mathematical abilities fall short of age norms.

Signs and Symptoms of Fragile X Syndrome

Children with fragile X syndrome exhibit several characteristic symptoms that can immediately raise suspicion among professionals after birth. Their facial structure differs from that of typically developing children, characterized by an elongated head, large protruding ears, and thick lips. Additionally, flat foot arches, enlarged testicles (macroorchidism), as well as hypotonic muscles and loose joints are frequently observed.

The weakness in connective tissues increases the risk of hernias, and affected children are also more susceptible to various infections. Furthermore, heart valve function may be abnormal, necessitating close medical monitoring. Various behavioral disorders are common among individuals with fragile X syndrome, which can be managed with medication.

The consequences of the syndrome are not limited to physical appearance. Affected children often struggle with speech and learning difficulties, which are reflected in their academic performance. In addition to delays in speech development, attention disorders may also occur, and children’s behavior can often be unusual, as they may be prone to repeating certain movements or displaying a blank expression. Their ability to establish social relationships is also challenging, and in many cases, they avoid eye contact. Their participation in school learning can be problematic, as learning to read and write often presents challenges, and their mathematical skills lag behind those of their peers.

Symptoms in Girls

Although fragile X syndrome primarily affects boys, symptoms can also appear in girls, typically in a milder form. In affected girls, cognitive and behavioral disorders often manifest at a later age. Instead of the characteristic symptoms seen in males, they may exhibit X chromosome-linked ovarian insufficiency or tremor and ataxia syndrome.

In some girls, the absence of menstruation may appear early, in young adulthood, leading to ovarian insufficiency. In others, symptoms resembling tremor and ataxia syndrome may present in their 30s or 40s. Thus, the symptoms and progression of the disease differ from those experienced by boys, but girls also face the impacts of fragile X syndrome.

Treatment of Symptoms and Future Outlook

The diagnosis of fragile X syndrome can be established even before birth. In cases where there are children with intellectual disabilities in the family, or if there is suspicion that the mother carries the disorder, genetic testing can be performed. This is crucial, as there is no cure for the disease in already born children, only symptom management.

The goal of treatment is to promote development, which typically requires speech and behavioral therapy. During therapy, children learn effective communication, to slow down their speech rate, and to facilitate social interactions. Since children with fragile X syndrome often have exceptionally good visual memory, images are frequently used to aid in word learning.

For children with delayed motor development, assistive devices such as special pens, keyboards, and mice are now available to facilitate usage. Additionally, the treatment of seizures, mood disorders, and other symptoms requires ongoing medical supervision. The scientific community continues to actively research potential treatment options for the disease in hopes of finding more effective solutions for managing fragile X syndrome in the future.