Causes of DiGeorge Syndrome
The primary cause of DiGeorge syndrome is a deletion in a small segment of chromosome 22, specifically at position q11.2. This missing piece contains around 30 to 40 genes. Many of which are important for the development of different organs and systems. When these genes are absent. The body’s development is affected in various ways, leading to the symptoms associated with DiGeorge syndrome.
Most cases of this syndrome are not inherited. The deletion occurs as a random event during the formation of reproductive cells (eggs or sperm) or in early foetal development. Therefore, parents usually have no control over whether the deletion occurs. However, in about 1 in 10 cases, one parent carries the same deletion and can pass it on to their child. This pattern of inheritance is known as autosomal dominant, which means there is a 50% chance of passing it on with each pregnancy.
Because DiGeorge syndrome arises from a genetic problem, it is usually present from birth, although the signs might not be immediately obvious. Genetic testing can confirm the diagnosis by identifying the 22q11.2 deletion. In South Africa, such tests are available through specialised clinics and laboratories, although access may be limited in rural areas.
Causes of DiGeorge Syndrome
Researchers continue to study the specific genes affected by this deletion. One of the most studied genes in this region is TBX1. This gene is believed to influence the development of the heart and face. Its absence likely explains the common heart defects and facial characteristics found in many children with DiGeorge syndrome.
In some cases, environmental factors during pregnancy may interact with genetic risks. However, no direct environmental cause has been found to trigger the deletion itself. This highlights the complexity of genetic conditions and the importance of specialised care and support for affected families.
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