Although CAIS is the most common form, resulting in feminization of a 46, XY fetus, there are other syndromes one must consider: SRY gene mutations, 5-α reductase deficiency, Swyer syndrome, 17-α-hydroxylase deficiency, and Smith-Lemli-Optiz syndrome.9 Here, SRY is linked to hyperinsulinemic hypoglycemia, familial, 4.