Is 22q11 DiGeorge Syndrome hereditary?
22q11 DiGeorge Syndrome, also known as 22q11.2 deletion syndrome, is a genetic disorder caused by a small missing piece of chromosome 22. This missing piece, known as a microdeletion, occurs in the region of chromosome 22q11.2. The syndrome is characterized by a wide range of symptoms that can affect various systems of the body, including the heart, immune system, and facial features.
Genetic Cause:
The genetic cause of 22q11 DiGeorge Syndrome is a spontaneous deletion of a small piece of chromosome 22. This deletion occurs during the formation of reproductive cells (sperm or egg) or early in fetal development. It is important to note that the deletion is not inherited from the parents, but rather arises as a new genetic change in the affected individual.
Reproductive Risk:
Although the deletion itself is not inherited, individuals with 22q11 DiGeorge Syndrome have a 50% chance of passing the syndrome on to each of their children. This is because the affected individual carries the deletion in their own reproductive cells (sperm or egg), which can be passed on to their offspring. However, it is important to understand that not all individuals with the deletion will have children, and the chance of passing on the syndrome depends on various factors.
Variable Penetrance:
One important aspect to consider is the concept of variable penetrance. This means that not all individuals who inherit the deletion will develop the full spectrum of symptoms associated with 22q11 DiGeorge Syndrome. Some individuals may have mild or no symptoms at all, while others may have more severe manifestations. The severity and specific symptoms can vary widely even among affected family members.
Genetic Counseling:
Given the variable nature of 22q11 DiGeorge Syndrome, genetic counseling is highly recommended for individuals and families affected by the syndrome. Genetic counselors are healthcare professionals with expertise in medical genetics who can provide information and support regarding the inheritance and recurrence risks of genetic conditions.
During a genetic counseling session, the counselor will review the medical history of the affected individual and their family, discuss the specific genetic cause of the syndrome, and provide information about the chances of passing on the syndrome to future children. They may also discuss available genetic testing options to determine the presence of the deletion in family members.
Genetic Testing:
Genetic testing can be performed to confirm the presence of the 22q11.2 deletion in an affected individual or to determine if they carry the deletion in their reproductive cells. This information can be valuable for family planning decisions and understanding the risk of passing on the syndrome.
Conclusion:
In summary, 22q11 DiGeorge Syndrome is caused by a spontaneous deletion of a small piece of chromosome 22. While the deletion itself is not inherited, affected individuals have a 50% chance of passing on the syndrome to each of their children. However, the severity and specific symptoms can vary widely among affected individuals, and not all individuals with the deletion will develop the full spectrum of symptoms. Genetic counseling and testing are important resources for individuals and families affected by 22q11 DiGeorge Syndrome to understand the inheritance risks and make informed decisions.