Introduction: Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder caused by impairment of one of the enzymes involved in the steroidogenesis pathway. CAH due to 21-hydroxylase deficiency (21-OHD) is attributed to mutations of the CYP21A2 gene and is distinguished into classic [salt wasting (SW), simple virilizing (SV)] and non-classic form. Herein we present a) the genetic investigation of 526 subjects with suspicion of 21-OHD in the last four years and b) the correlation of 17-hydroxyprogesterone (17-OHP) concentrations after ACTH stimulation test in heterozygotes and genotypically negative individuals.
Patients and Methods: 526 subjects (75% girls, 25% boys) with a mean age of 9 years (3 days-77 years) were referred for genetic analysis of the CYP21A2 gene. The majority of referrals were due to premature adrenarche. Sanger sequencing CYP21A2 gene was carried out in all individuals (and parents when available). MLPA analysis was also performed when duplication/deletion was suspected. A total of 950 parents were analyzed. Two different approaches were applied for the correlation of 17-OHP concentrations, i. Difference 17-OHP(60΄) – 17-OHP(0΄) and ii. Sum 17-OHP(30΄)+17-OHP(60΄) with genotype.
Results: Genetic diagnosis of CAH was achieved in 30% of cases (22% compound heterozygotes and 7.8% homozygotes). 37% of the referrals were found to be heterozygotes (16% heterozygotes for a classic and 84% for a non-classic CYP21A2 mutation). 2.5% harbored a CYP21A2 duplication. No mutation was identified in 31% of the cases. Genotyping of the parents identified 29/950 (3%) compound heterozygotes/homozygotes for the non-classic form of 21-OHD. Table 1 presents the % of the cases where genotype correlates with the 17-OHP values. It should be stated that the best correlation of 17-OHP concentrations and genotype is provided by the p.P30L (94.1%) while the c.*13G>A shows a poor correlation with 17-OHP concentrations (60%) for both approaches tested.
|Genotype||Number||17-OHP(60΄)-17-OHP(0΄) Cut-off for heterozygotes >3.6ng/μL||17-OHP(60΄)+17-OHP(30΄) Cut-off for heterozygotes >10.1ng/μL|
|p.P30L/Ν||17||16 (94.1%)||16 (94.1%)|
|p.V281L/Ν||55||44 (80%)||49 (89.1%)|
|p.P453S/Ν||19||16 (84.2%)||16 (84.2%)|
|c.*13G>A/Ν||15||9 (60%)||9 (60%)|
|Ν/Ν||123||77 (62.6%)||46 (37.4%)|
Discussion: The two different approaches for the correlation of stimulated 17-OHP concentrations and genotype cannot successfully distinguish the heterozygotes and the genotypically negative examined individuals highlighting the importance of molecular genetic analysis in order to confirm the clinical diagnosis, patient prognosis and genetic counselling.
15 Sep 2022 - 17 Sep 2022