Plasma 17-hydroxyprogesterone determination with two commercial immunoassays

A New Homozygous Frameshift Mutation in the HSD3B2 Gene in an Apparently Nonconsanguineous Italian Family

BACKGROUND

3β-Hydroxysteroid dehydrogenase (3β-HSD) deficiency is a rare cause of congenital adrenal hyperplasia (CAH) caused by inactivating mutations in the HSD3B2 gene.

PATIENT AND METHODS

We report the molecular and structural analysis of the HSD3B2 gene in a 46,XY child born to apparently nonconsanguineous parents and presenting ambiguous genitalia and salt wasting. The steroid profile showed elevated concentrations of 17-hydroxyprogesterone, androstenedione, ACTH and plasma renin, but normal values of cortisol and dehydroepiandrosterone sulfate. Unexpectedly, plasma aldosterone was high. For structural and functional analyses, the three-dimensional structure of 3β-HSD2 was modeled using the crystal structure of the short-chain dehydrogenase Gox2253 from Gluconobacter oxydans as a template.

RESULTS

The direct DNA sequence of the child revealed a new homozygous frameshift mutation in exon 4 of the HSD3B2 gene, a single nucleotide deletion at codon 319 [GTC(Val)x2192;GC], yielding premature stop codon in position 367. Molecular homology modeling and secondary structure predictions suggested that the variant sequence might both alter the substrate-binding cleft and compromise the overall stability of the enzyme.

CONCLUSION

We have described the first HSD3B2 gene mutation in the Italian population and analyzed its effect in the context of the 3β-HSD2 structure and function.

17alpha-hydroxyprogesterone and cortisol serum levels in neonates and young children: influence of age, gestational age, gender and methodological procedures

To determine the influence of age, gestational age, gender and methodological protocol on serum 17OHP and cortisol concentrations. 17OHP in non-extracted (NE) and extracted (E) sera was measured by RIA in 319 full-term (FT) (1 d-5 yr) infants, 38 pre-term (PT) and in 19 neonates with classical CAH at diagnosis. 17OHP (NE- and E-) decreased with age in normal children. The extraction procedure significantly reduced 17OHP by eliminating interfering steroids in children < 1 year. Sexual dimorphism was only observed in NE-17OHP. 17OHP in PT was always higher than in FT up to 2 months of age (p < 0.001). Neither NE- nor E-17OHP in CAH overlapped with those of FT or PT (p < 0.001) allowing to omit the extraction procedure to confirm CAH diagnosis. Cortisol levels were within normal range in neonates with CAH, thus not adding useful information about adrenal function. Chronological and gestational age, gender, and extraction for 17OHP measurement are important factors to know when assessing adrenal function during the first year of life.

Determination of 17α‐hydroxyprogesterone in serum by liquid chromatography‐tandem mass spectrometry and immunoassay

17Alpha-hydroxyprogesterone (17OHP) is the most important serum marker for congenital adrenal hyperplasia (CAH). 17OHP is usually measured by immunoassay but its detection by mass spectrometry (MS) is a potentially superior method. An LC-MS (liquid chromatography-mass spectrometry) method was developed which utilizes 0.5 ml serum spiked with 6-alpha-methylprednisolone (6-MP) or deuterated 17OHP (d8-IS) as the internal standard. The samples were extracted with ether/ethylacetate, and the extract was evaporated to dryness and analysed by LC-MS/MS operating in the positive mode after separation on a reversed-phase C18 column. The calibration curves for analysis of serum 17OHP exhibited consistent linearity and reproducibility in the range of 5-250 nmol/l. Interassay CVs were 8.5 and 9.2% at mean concentrations of 7.9 and 23 nmol/l, respectively. The detection limit was 1 nmol/l (signal-to-noise ratio=3). The mean recovery of 17OHP added to serum ranged from 76 to 89% and that of internal standards from 75 to 82%. The regression equation for the LC-MS/MS (x) and in-house radioimmunoassay (RIA) (y) methods was: y=0.87x+0.26 (r=0.97; n=100) and for a commercial RIA it was: y=1.32x+0.02 (r=0.97; n=26).

Diagnosis of congenital adrenal hyperplasia by rapid determination of 17alpha-hydroxyprogesterone in dried blood spots by gas chromatography/mass spectrometry following microwave-assisted silylation

17alpha-Hydroxyprogesterone (17OHP) is considered to be the biomarker of congential adrenal hyperplasia (CAH). Screening for CAH in newborns by measuring levels of the biomarker of 17OHP has become routine. In the work, a rapid, simple and sensitive technique was developed for the diagnosis of neonatal CAH by the quantitative analysis of 17OHP in neonatal blood spots. The technique was based on microwave-assisted silylation (MAS) followed by gas chromatography/mass spectrometry (GC/MS). In the method, fast derivatization of 17OHP with N,O-bis(trimethylsilyl)trifluoroacetamide was performed by using microwave irradiation, and the trimethylsilyl derivative thus formed was analyzed by GC/MS. The results of the experiment indicate that MAS followed by GC/MS analysis is a rapid, simple and sensitive method for the determination of 17OHP in blood samples. The proposed technique has been shown to have potential as a powerful tool for the rapid diagnosis of neonatal CAH.

Rapid screening assay of congenital adrenal hyperplasia by measuring 17 alpha-hydroxyprogesterone with high-performance liquid chromatography/electrospray ionization tandem mass spectrometry from dried blood spots

A rapid, simple, and specific method was developed for the diagnosis of congenital adrenal hyperplasia (CAH) from dried blood spots on newborn screening cards based on high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS). The usefulness of 17 alpha-hydroxyprogesterone (17 OH-P) determination on dried filter-paper blood samples from patients with CAH caused by 21-hydroxylase deficiency was evaluated. The LC/MS/MS detection of 17 OH-P was rapid, <4 min. The intra- and interday accuracy and precision of the method were <7%. Our procedure maintained good linearities (R(2) > 0.992) and recovery rate (>83%). We used this new method to directly determine the 17 OH-P levels in dried blood specimens from abnormal children of various ages, with a detection limit of 20 ng/ml (approximately 240 pg), to avoid the time-consuming derivatization steps required by the gas-chromatography/mass spectrometry (GC/MS) method. Four dried filter-paper blood samples of CAH patients (three girls and one boy, 1-14 years old) were all quantified in an LC/MS/MS study and revealed high 17 OH-P levels (>90 ng/ml). After treatment, all of the elevated 17 OH-P levels either decreased or disappeared. Compared with CAH patients, 17 OH-P was nearly undetectable (<20 ng/ml) in the normal infants by LC/MS/MS. This LC/MS/MS assay is not only useful for both diagnosis and monitoring of treatment of CAH in all other age groups, it also can be used as a screening test for CAH infants. In this study, we provided the first data on 17 OH-P in dried blood specimens affected with CAH using HPLC/ESI-MS/MS.

Rapid monitoring assay of congenital adrenal hyperplasia with microbore high-performance liquid chromatography/electrospray ionization tandem mass spectrometry from dried blood spots

17-hydroxyprogesterone (17OHP) is the most important plasma parameter for diagnosing and monitoring congenital adrenal hyperplasia (CAH) caused by 21-hydroxylase deficiency. A rapid, simple, and specific method based on microbore high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (micro-HPLC/ESI-MS/MS) was developed to determine the presence of 17OHP on dried filter-paper blood samples from patients with CAH caused by 21-hydroxylase deficiency. 17OHP from dried blood spots formed by the action of Girard reagent P (GirP) turned out to be a water-soluble hydrazone complex. Derivatization with GirP led to higher ESI sensitivity for 17OHP. The LC/MS/MS detection of GirP-derivatized 17OHP (GirP-17OHP) was rapid (<3 min). The method is repeatable and reproducible, with CVs <7% and 12%, respectively. This new method was used for direct determination of 17OHP in dried blood specimens obtained from abnormal children and infants of various ages with a detection limit of 10 ng/mL ( approximately 12 microL blood). The method described allows for rapid and reliable measurements of 17OHP in dried blood specimens from patients affected by CAH.