22q112 Deletion Syndrome (DiGeorge Syndrome or Velocardiofacial Syndrome)
Description
22q11.2 Deletion Syndrome, also known as DiGeorge Syndrome or Velocardiofacial Syndrome, is a genetic disorder caused by a missing piece of chromosome 22. This deletion affects various parts of the body, resulting in a range of physical, developmental, and learning challenges. This comprehensive guide provides information on recognizing the signs and symptoms, understanding its causes, inheritance patterns, diagnosis, management strategies, and ways to support individuals with 22q11.2 Deletion Syndrome to thrive.
Genes Involved
The 22q11.2 Deletion Syndrome is caused by a deletion of a segment of chromosome 22, encompassing a region containing numerous genes. Some of the key genes involved in the syndrome include:
- TBX1: A gene crucial for heart development and other structures in the head and neck.
- COMT: This gene plays a role in neurotransmitter metabolism and is associated with cognitive function.
- DGCR8: This gene is involved in the processing of microRNAs, essential for various cellular processes.
Recognizing the Signs and Symptoms
Individuals with 22q11.2 Deletion Syndrome can experience a wide spectrum of symptoms, with varying severity. Common features include:
- Heart defects: Congenital heart defects, such as tetralogy of Fallot or ventricular septal defect, are prevalent.
- Facial features: Characteristic facial features may include a wide-set nose, small chin, and a slightly upturned nose.
- Palate problems: Cleft palate or a high-arched palate can occur.
- Immune system issues: Recurrent ear infections, respiratory problems, and increased susceptibility to infections can be present.
- Developmental delays: Learning difficulties, speech and language delays, and behavioral challenges are possible.
- Other potential issues: Hypocalcemia (low calcium levels), kidney problems, and mental health conditions may also be associated with the syndrome.
Causes
22q11.2 Deletion Syndrome arises from a spontaneous deletion of a small segment of chromosome 22 during the formation of the egg or sperm cell. This deletion occurs randomly and is not inherited from the parents. In rare cases, the deletion can be inherited from a parent who carries a balanced translocation (where a piece of chromosome 22 is swapped with another chromosome).
Inheritance/recurrence risk
While the deletion itself is not usually inherited, there is a small risk of recurrence in subsequent pregnancies. If one child has 22q11.2 Deletion Syndrome, the chances of having another child with the same condition are estimated to be around 1-3%. However, this risk is dependent on whether the deletion occurred in the parent‘s egg or sperm cell and the specific type of deletion.
