These data are in agreement with the absence of MEN1 mRNA expression of MEN1-LOH parathyroid adenomas and high MEN1 mRNA expression levels in the sporadic parathyroid adenomas and in normal parathyroid tissue (Fig. 4A), but for the 50% expression level shown by MEN1 parathyroid adenomas that conserved one wild-type copy of MEN1 gene (without MEN1-LOH), which should theoretically express half of the menin protein (Fig. 4A). This evidence concerns the gene MEN1 and parathyroid gland adenoma.