Nijmegen Breakage Syndrome
Patients are characterized by microcephaly and a bird-like facies: sloping forehead, receding mandible, long nose, and upward slanted palpebral fissures. These features become more prominent as patients become older. The immunodeficiency in NBS is characterized by agammaglobulinemia (30%), IgA deficiency, or IgG subclass deficiency. In addition, the majority of patients have T cell lymphopenia and decreased T cell function.