The hormonal phenotype of Nonclassic 3 beta-hydroxysteroid dehydrogenase (HSD3B) deficiency in hyperandrogenic females is associated with insulin-resistant polycystic ovary syndrome and is not a variant of inherited HSD3B2 deficiency.

To test our hypothesis that the hormonal phenotype of mild 3beta-hydroxysteroid dehydrogenase (HSD3B) deficiency in hyperandrogenic females (HF) is related to insulin-resistant polycystic ovary syndrome (PCOS), we compared insulin sensitivity and gonadotropin secretion in HF with compromised ( downward arrow ) adrenal HSD3B phenotype despite normal HSD3B2 genes (n = 6) to those in HF with classic PCOS (n = 9) of similar ages (14-36 yr). The same was examined in premature pubarche (PP) girls with (n = 4) and without the descending HSD3B phenotype (n = 5). The descending HSD3B phenotype was defined by ACTH-stimulated Delta(5)-precursor steroid levels and Delta(5)-precursors to Delta(4)-product steroid ratios higher than those in normal females (n = 30 for adult, n = 12 for pubertal). Classic PCOS HF had elevated testosterone levels and normal ACTH-stimulated hormonal profiles. The insulin sensitivity index determined by the frequently sampled iv glucose-tolbutamide test (FSIVGTT) in all HF with descending HSD3B phenotype and in all HF with classic PCOS, regardless of body mass index (BMI), was lower than in all eight normal BMI and five high BMI normal females. Integrated incremental insulin determined by FSIVGTT, the area under the curve for insulin, and fasting and 2 h glucose load insulin levels determined by an oral glucose tolerance test in both HF groups were higher (P < 0.01-0.0001) than those in normal females with normal or high BMI. LHRH-stimulated LH levels and LH/FSH ratios in both HF groups were higher (P < 0.01) than those in normal females. No statistical differences were found in the insulin sensitivity and gonadotropin parameter between the two PP girl groups. The insulin sensitivity index in each half of PP girls with the descending HSD3B phenotype was lower than or similar to that in control PP girls with a similar weight length index. The fasting glucose to insulin ratio in three of four PP girls with the descending HSD3B phenotype was lower than that in control PP girls, but one of four with the descending HSD3B phenotype had a higher fasting glucose to insulin ratio than the control PP girls. The findings of insulin sensitivity and gonadotropin data in both HF with the descending HSD3B phenotype and classic PCOS indicate significant insulin resistance and LH hypersecretion in both. These suggest that the descending HSD3B phenotype in HF is associated with a variant of insulin-resistant PCOS. The variable insulin sensitivity parameter in the small number of PP girls with the descending HSD3B phenotype warrants a further large scale study to examine this phenotype association with childhood insulin resistance.

Carriers for type II 3beta-hydroxysteroid dehydrogenase (HSD3B2) deficiency can only be identified by HSD3B2 genotype study and not by hormone test.

OBJECTIVE: We investigated adrenal steroidogenic function relevant to 3beta-hydroxysteroid dehydrogenase (HSD3B2) activity in vivo and HSD3B2 genotype in clinically normal family members of patients with HSD3B2 genotype-proven HSD3B2 deficiency congenital adrenal hyperplasia (CAH) to determine whether genotype-proven carriers for HSD3B2 deficiency exhibit decreased enzyme activity analogous to the mildly decreased adrenal 21-hydroxylase activity in the carriers of CYP21 gene mutation. DESIGN/PATIENTS: Nineteen adult family members (ages median/range: 37/19-56 years) including 13 females and six males of six unrelated patients with HSD3B2 genotype-proven HSD3B2 deficiency were studied. MEASUREMENTS: All family members had HSD3B2 DNA analysis and an ACTH stimulation test (Cortrosyn 0.25 mg IV bolus) for determination of adrenal HSD3B activity. RESULTS: Ten of 13 females and five of six males were carriers of a proven or predictably deleterious mutation in one allele of the HSD3B2 gene, which was identified in the probands. ACTH-stimulated levels of 17-hydroxypregnenolone (delta5-17P), 17-hydroxyprogesterone (17-OHP), cortisol (F), dehydroepiandrosterone (DHEA) and androstenedione (delta4-A) and ratios of delta5-17P to 17-OHP, delta5-17P to F and DHEA to delta4-A, as well as increments of delta5-17P and DHEA values (ACTH-stimulated - baseline) in the genotype-proven female carriers (age, mean +/- SD: 36 +/- 6.7 years) and male carriers (age, mean +/- SD: 37 +/- 6.7 years) did not differ significantly from age-matched normal females (35 +/- 5.4 years, n = 20) and normal males (35 +/- 6 years, n = 10), respectively. There were no significant differences in any of the ACTH-stimulated hormonal levels or ratios between the female carriers with a seriously deleterious genotype (n = 5) and the female carriers with mildly deleterious genotypes (n = 5). These hormonal levels and ratios in three genotype-normal females and one genotype-normal male overlapped with those of the carriers. CONCLUSION: These data suggest that normal adrenal HSD3B2 activity is maintained in the genotype-proven carriers because heterodimers of mutant and wild-type HSD3B2 enzymes may be stable and exhibit similar activity compared to homodimers of wild-type enzymes, possibly by a relatively rate-unlimited effect of haplo-wild-type enzyme activity. However, we cannot preclude entirely the possibility of a limited expression of another HSD3B activity under ACTH stimulation contributing to the normal adrenal HSD3B activity in vivo in the HSD3B2 genotype-proven heterozygotes. Which mechanism plays a role in maintaining normal enzyme activity in the heterozygotes remains to be elucidated. The hormone findings in the genotypic-proven carriers for HSD3B2 deficiency also indicate that carriers for this disorder cannot be detected by a hormone test and can only be detected by HSD3B2 genotype study.

A novel nonstop mutation in the stop codon and a novel missense mutation in the type II 3beta-hydroxysteroid dehydrogenase (3beta-HSD) gene causing, respectively, nonclassic and classic 3beta-HSD deficiency congenital adrenal hyperplasia.

We investigated two novel point mutations in the human type II 3beta-hydroxysteroid dehydrogenase (3beta-HSD) gene causing a mild and a severe form of 3beta-HSD deficiency congenital adrenal hyperplasia. The first is a nonstop mutation in the normal stop codon 373 of the gene in exon IV [TGA (Stop) --> TGC (Cys) = Stop373C) identified from one allele of a female child with premature pubarche whose second allele had an E142K mutation. The Stop373C mutation predictably results in an open reading frame and a mutant-type (MT) II 3beta-HSD protein containing 467 amino acid residues, compared with the 372 amino acid residues of wild-type (WT) protein. The second is a homozygous missense mutation in codon 222 [CCA (Pro) --> ACT (Thr) = P222T] in the gene identified from a female neonate with salt-wasting disorder. The pcDNA vectors containing the constructs of WT II 3beta-HSD cDNA, WT cDNA with the open reading frame (WT cDNA(+)), MT Stop373C with the open reading frame (Stop373C(+)) and MT P222T cDNA were transfected in COS-I and 293T cells and expressed a similar amount of 3beta-HSD mRNA. The enzyme activity in intact cells using pregnenolone and dehydroepiandrosterone as substrate in the medium (1 micromol/liter) was identical between the WT cDNA and the WT cDNA(+), but was decreased to 27% of the WT enzymes at 6 h by MT Stop373C(+) enzyme, and was undetectable by P222T enzyme. In the homogenates of the cells, both MT Stop373C(+) and P222T enzyme activities and enzymes were undetectable despite clear detection of WT enzyme activities and WT enzymes. LH response to an LHRH analog stimulation in the pubertal female with the Stop373C/E142K genotypes and in a pubertal female with compound 273/318 frameshift genotypes were comparable to and higher than control females, respectively. In conclusion, a structurally lengthy MT II 3beta-HSD enzyme due to a nonstop mutation was relatively detrimental in intact cells causing the nonclassic phenotype of 3beta-HSD deficiency. A missense P222T mutation was seriously detrimental, causing the classic phenotype of 3beta-HSD deficiency. The undetectable Stop373C and P222T enzymes on Western blottings, together with the respective in vivo and in vitro data, suggest that a relative instability of Stop373C enzyme and a profound instability of the P222T enzyme are likely the detrimental molecular mechanisms. The increased LH in the female with the frameshift genotype and the appropriate LH response in the female with the nonstop genotype correlated with predictably severe and mild ovarian type II 3beta-HSD deficiency, respectively.