All of the following are seen in 22q 11.2 deletion syndrome except
**Core Concept**
22q11.2 deletion syndrome, also known as DiGeorge syndrome, is a genetic disorder characterized by the deletion of a segment of chromosome 22. This deletion affects various developmental processes, including embryonic development, and leads to a range of clinical manifestations.
**Why the Correct Answer is Right**
The correct answer is related to the characteristic features of 22q11.2 deletion syndrome. This condition is associated with thymic hypoplasia, leading to impaired T-cell development and increased susceptibility to infections. Patients often exhibit characteristic facial features, such as a pointed chin and prominent nose, and may also have cardiac anomalies, including tetralogy of Fallot. Additionally, they may experience developmental delays, behavioral problems, and an increased risk of schizophrenia.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because patients with 22q11.2 deletion syndrome typically have a reduced number of T cells, which increases their susceptibility to infections, particularly of the respiratory tract. They do not exhibit an increased number of T cells.
**Option B:** This option is incorrect because congenital heart block is more commonly associated with autoimmune disorders, such as lupus or rheumatoid arthritis, rather than 22q11.2 deletion syndrome. Tetralogy of Fallot, however, is a cardiac anomaly that can be seen in this condition.
**Option C:** This option is incorrect because patients with 22q11.2 deletion syndrome often have a reduced number of parathyroid glands, leading to hypocalcemia, rather than hypercalcemia.
**Clinical Pearl / High-Yield Fact**
A key clinical feature of 22q11.2 deletion syndrome is the presence of characteristic facial features, including a pointed chin and prominent nose. These features can be a useful clue in diagnosing this condition.
**Correct Answer: C. Hypercalcemia**