Examples include X-linked disorders such as X-linked lymphoproliferative disorder (XLP) and MAGT1 deficiency, and autosomal recessive disorders such as CD27 deficiency, CD70 deficiency, ITK deficiency, RASGRP1 deficiency, CTPS1 deficiency, CORO1A deficiency and DOCK8 deficiency. Here, ITK is linked to hyperinsulinemic hypoglycemia, familial, 4.