You are called urgently to examine a term, 2-hour-old newborn who has had temperature instability, difficulty with feeding, and a sus- pected seizure. He has atypical facies (wide-set eyes, a prominent nose, and a small mandible), a cleft palate, and a holosystolic murmur. Stat laboratory tests and chest radiograph reveal marked hypocalcemia, a boot-shaped heart, and no apparent thymus. Which of the following is the most likely diagnosis?

A. Ataxia–telangiectasia
B. DiGeorgesyndrome
C. Hyper-IgE syndrome
D. SCID
E. Wiskott-Aldrich syndrome