Additional evidence to suspect BCL10 deficiency may include the absence or severe reduction of memory B and memory T cells and reduced levels of circulating immunoglobulins, comparable to those of patients with hypogammaglobulinemia, as this phenotype has been observed in all 3 reported cases of BCL10 deficiency (29, 30). This evidence concerns the gene BCL10 and hyperinsulinemic hypoglycemia, familial, 4.