A 6-month-old infant presents with poor weight gain, recurrent diarrhea

A 6-month-old infant presents with poor weight gain, recurrent diarrhea

A 6-month-old infant presents with poor weight gain, recurrent diarrhea, and oral thrush. Laboratory tests show lymphopenia and low IgG levels. Which immunodeficiency disorder is most likely?

A. Severe combined immunodeficiency (SCID)

B. X-linked agammaglobulinemia

C. Common variable immunodeficiency

D. DiGeorge syndrome

E. Wiskott-Aldrich syndrome

Answer: A

Explanation: SCID is a severe primary immunodeficiency characterized by profound defects in both B and T cell function, presenting in infancy with failure to thrive, recurrent infections (including fungal infections like oral thrush), lymphopenia, and low immunoglobulin levels.