A 12-month-old infant with a history of recurrent infections, eczema, generalized edema, and easy bruising is diagnosed with an X-linked, recessive, congenital immunodeficiency. The CBC shows thrombocytopenia. What is the most likely diagnosis?
**Core Concept**
The question is testing the understanding of X-linked, recessive, congenital immunodeficiencies, particularly those affecting the immune system's ability to fight off infections, cause eczema, and lead to bleeding tendencies due to thrombocytopenia.
**Why the Correct Answer is Right**
The patient's symptoms of recurrent infections, eczema, generalized edema, easy bruising, and thrombocytopenia are characteristic of Wiskott-Aldrich Syndrome (WAS), an X-linked, recessive disorder caused by mutations in the WAS gene. This gene encodes the WAS protein (WASp), which is crucial for the normal functioning of platelets, T cells, and B cells. Without WASp, platelets are smaller and fewer in number, leading to thrombocytopenia, while T cells are dysfunctional, leading to recurrent infections. The eczema and generalized edema are secondary to the immune dysfunction.
**Why Each Wrong Option is Incorrect**
**Option A:** **Severe Combined Immunodeficiency (SCID)**. SCID is a group of disorders characterized by severe impairment of both T cell and B cell function, leading to recurrent infections. While SCID is an X-linked disorder, it does not typically present with thrombocytopenia or eczema.
**Option B:** **Leukocyte Adhesion Deficiency (LAD)**. LAD is a disorder of leukocyte adhesion, leading to recurrent infections. However, it does not typically present with thrombocytopenia or eczema.
**Option C:** **Di George Syndrome**. Di George Syndrome is a disorder caused by 22q11.2 deletion, leading to thymic hypoplasia and impaired T cell development. While it can cause recurrent infections, it does not typically present with thrombocytopenia or eczema.
**Option D:** **Chronic Granulomatous Disease (CGD)**. CGD is a disorder of phagocytic cell function, leading to recurrent infections. However, it does not typically present with thrombocytopenia or eczema.
**Clinical Pearl / High-Yield Fact**
Wiskott-Aldrich Syndrome is a classic exam trap, and its diagnosis requires a high index of suspicion in infants with recurrent infections, eczema, and bleeding tendencies. Remember the "triad" of symptoms: eczema, thrombocytopenia, and recurrent infections.
**Correct Answer: C. Di George Syndrome is incorrect due to the presence of thrombocytopenia. The correct answer is actually: D. **