MMR deficiencies, with regard to hMLH1, were detected in seven of 38 patients (18.4%; 95% CI, 7.7–34.3), and a loss of hMSH2 expression was detected in three of the 38 patients (7.9%; 95% CI, 1.7–21.4). This evidence concerns the gene MSH2 and hyperinsulinemic hypoglycemia, familial, 4.