A small case-control trial to determine the relevance of protein S deficiency in HIV patients by Mochan et al. in 2005 found a statistically significant association between protein S deficiency and stroke, concluding that protein S deficiency in HIV-positive patients with stroke is an epiphenomenon of the HIV infection [12]. The gene discussed is PROS1; the disease is hyperinsulinemic hypoglycemia, familial, 4.