ALLERGY AND ASTHMA :: Immune Deficiencies
The Thymus and Parathyroid Glands
The thymus gland is located behind the breastbone and is responsible for the maturation of T-cells to fight infections. The four parathyroid glands are located adjacent to the thyroid gland in the neck and regulate calcium in the blood through the production of parathyroid hormone.
What is DiGeorge syndrome?
DiGeorge Syndrome is a genetic disorder with varying conditions present in each individual with the syndrome. However, conditions that are common to the syndrome include certain heart defects, effects on facial appearance, and lack of or underdeveloped thymus and parathyroid glands.
The history of the syndrome, previously referred to as DiGeorge, includes the following discoveries:
What is velo-cardio-facial syndrome (VCFS)?
Velo-cardio-facial syndrome (VCFS) is a genetic condition that is related to DiGeorge Syndrome. VCFS involves a similar chromosome abnormality as DiGeorge Syndrome.
What causes DiGeorge syndrome?
As mentioned, 90 percent of patients with the features of this syndrome are missing a small part of their chromosome 22 at the q11 region. This region encompasses about 30 individual genes and results in developmental defects in specific structures throughout the body. It is not known why this region of chromosome 22 is prone to become deleted, but this is one of the most frequent chromosome defects in newborns. Deletion 22q11 is estimated to occur in one in 3,000 to 4,000 live births. Most of the 22q11 deletion cases are new occurrences or sporadic (occurs by chance). However, in about 10 percent of families, the deletion is inherited and other family members are affected or at risk for passing this deletion to their children. The gene is autosomal dominant, therefore, any person who has this deletion has a 50 percent chance of passing the deletion to a child. For this reason, whenever a deletion is diagnosed, both parents are offered the opportunity to have their blood studied to look for this deletion.
Approximately 10 percent of individuals who have the features velo-cardio-facial syndrome (VCFS) do not have a deletion in the chromosome 22q11 region. Other chromosome defects have been associated with these features, as have maternal diabetes, fetal alcohol syndrome, and prenatal exposure to Accutane® (a medication for cystic acne).
What are the features of DiGeorge syndrome?
The following are the most common features of DiGeorge syndrome. However, not every child will have every feature of the syndrome and the severity of the features will vary between children. Features may include:
Facial features of children with DiGeorge syndrome may include the following:
The symptoms of DiGeorge syndrome may resemble of problems or medical conditions. Always consult your child's physician for a diagnosis.
How is DiGeorge syndrome diagnosed?
In addition to a prenatal history, complete medical and family history, and a physical examination, diagnostic procedures for DiGeorge may include:
Treatment for DiGeorge syndrome:
Specific treatment for DiGeorge syndrome will be determined by your child's physician based on the following:
Treatment will also depend on the particular features in any given child and may include the following:
In severe cases where immune system function is absent, bone marrow transplantation is required.
Many newborns with this deletion will benefit from early intervention to help with muscle strength, mental stimulation, and speech problems. Basically, treatment is dependent upon the specific symptoms seen in any given child.
Long-term outlook for children with DiGeorge syndrome:
A small percentage of children with severe heart defects and immune system problems will not survive the first year of life. However, with the proper treatment of heart defects, immune system disorders, and other health problems, the vast majority of children with a 22q11 deletion will survive and grow into adulthood. These children will generally need extra help throughout school and will need long term care for their individual health needs.
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It is important to remember the health information found on this website is for reference only not intended to replace the advice and guidance of your healthcare provider. Always seek the advice of your physician with any questions you may have regarding a medical condition. If you think you may have a medical emergency, call your physician or 911 immediately.
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