COMMENTS - STEROID 21-HYDROXYLASE MUTATIONS AND 21-HYDROXYLASE MESSENGER-RIBONUCLEIC-ACID EXPRESSION IN HUMAN ADRENOCORTICAL TUMORS

Twenty-one hydroxylase (P450c21) is a key enzyme essential for normal zona glomerulosa and fasciculata function. Recently, 21-hydroxylase de ficiency has been implicated in the pathogenesis of adrenocortical tum ors. Therefore, we investigated the mutational spectrum of the CYP21B gene and the messenger RNA expression of P450c21 in six aldosterone-pr oducing adenomas, seven cortisol-producing adenomas, two nonfunctional incidentally detected adenomas, and four adrenal carcinomas. DNA from leukocytes and tumors was amplified by PCR using primers specific for the CYP21B gene. The 10 exons, intron 2, intron 7, all other exon/int ron junctions, and 380 bp of the promoter region of CYP21B were automa tically sequenced. Poly(A) RNA was extracted from tumor tissue, dot bl otted on a nylon membrane, and hybridized with P-32-labeled P450 side- chain cleavage, P450 17-alpha-hydroxylase, and P450c21 complementary D NA probes. We detected heterozygous germline mutations (exon 7, Val 28 1Leu) in two patients, one with a cortisol-producing adenoma and the o ther with an androgen-secreting adrenocortical carcinoma. A somatic, h eterozygous microdeletion was found in exon 3 of one aldosterone-produ cing adenoma. The P450c21 gene expression correlated with the clinical phenotype of the tumor, with low P450c21 messenger RNA expression in nonfunctional adenomas (18.8%, 1.5%) compared with high P450c21 expres sion in aldosterone- and cortisol-producing adenomas (84 +/- 8% and 10 1 +/- 4%, respectively, us, normal adrenals, 100 +/- 10%). In conclusi on, the prevalence of heterozygous germline mutations in the CYP21B ge ne was higher in patients with adrenocortical tumors (11%; 95% confide nce interval, 1-34%) than in the general European population (2%; 95% confidence interval, 1.93-2.06%), but this difference is questionable because of the low number of subjects in our series. The pathophysiolo gical significance of this finding in the presence of one normal CYP21 B gene seems to be low, suggesting that 31-hydroxylase deficiency is n ot a major predisposing factor for adrenal tumor formation.