MBL deficiency, due to variation in the MBL gene, is one of the most common immunodeficiencies [5,12] and is associated with impaired phagocytosis by polymorphonuclear leukocytes and with an increased burden of infections, especially in immunocompromised individuals [13-15]. Here, MBL2 is linked to hyperinsulinemic hypoglycemia, familial, 4.