High incidence of molecular defects of the CYP21 gene in patients with premature adrenarche.

On the basis of hormonal studies, the incidence of defective steroidogenesis in children with premature adrenarche (PA) in the various reports ranges from 0-54%. Molecular studies have not been reported to date. The aim of the present study was to search for defects in the CYP21 gene in children with PA and to detect possible correlations of the molecular defect to pertinent hormonal and clinical data. In 48 children with PA (40 females and 8 males) and without signs of virilization, a Synachten test and molecular studies were carried out. DNA analysis was performed using the Southern blot technique and allele-specific PCR. Synachten (0.25 mg) was given i.v., and 17-hydroxyprogesterone and cortisol were determined at 0 and 60 min. At baseline, delta4-androstenedione, dehydroepiandrosterone sulfate, and 11-deoxycortisol were also determined. Bone age was evaluated using the Greulich and Pyle atlas. Abnormal genotype was detected in 45.8% of the studied subjects; 8.3% were homozygotes, with genotypes concordant with the nonclassical phenotype of 21 hydroxylase deficiency, and 37.5% were heterozygotes for 9 different molecular defects of the CYP21 gene. The children with no detectable molecular defect were designated normal. The 60 min post-Synachten values in homozygotes (17.9 +/- 7.1 ng/mL) and heterozygotes (7.1 +/- 3.6 ng/mL) were significantly higher than that in normal subjects (3.3 +/- 1.5 ng/mL), but with significant overlapping of values. The mean difference between bone age and chronological age differed in the three groups with overlapping values. The basal delta4-androstenedione level was lower in the normal subjects (0.65 +/- 0.3 ng/mL) than in those with abnormal genotype (1.1 +/- 0.8 ng/mL). The data indicate that the incidence of molecular defects in PA is quite high. The CYP21 heterozygocity is clinically expressed in some subjects prepubertally. In a significant number of cases the genotype cannot be predicted by the age of onset of PA, the mean difference between bone age and chronological age, or the results of a Synachten test. Follow-up of these children through puberty is imperative and may reveal the clinical significance of the molecular defect, namely more hypertrichosis, intense acne, early puberty, possible abnormal menses, and/or fertility problems in the affected.