Aurora, an 18-month-old girl, is brought to the clinic because of frequent respiratory and ear infections. At first glance, you notice she has some small dilated blood vessels over the sclera of her eyes. Upon physical examination, you also realize that she has a delay in speech, as well as frequent stumbling when walking. Laboratory studies are obtained, showing a low lymphocyte count, low immunoglobulin levels, and high alpha-fetoprotein or AFP.
Next comes Mathew, a 16-month-old boy that’s brought to the clinic because of a skin rash that appeared on his back since infancy and won’t go away. Mathew’s mother also tells you that he has frequent spontaneous nosebleeds and has had recurrent respiratory tract infections over the last few months. Laboratory studies are obtained, revealing that Mathew’s platelets are quite small in size and fewer than normal, while the immunoglobulins IgA…
