THE ROLE OF 21-HYDROXYLASE DEFICIENCY IN THE PATHOGENESIS OF BEHÇET DISEASE.

Objective: Acne-like skin lesions and more severe disease course in males suggest a role for sex hormones in the pathogenesis of Behçet disease (BD). HLA-B51 is the main genetic susceptibility factor for BD, and CYP21A2 gene responsible for most of congenital adrenal hyperplasia (CAH) is located within the MHC locus on chromosome 6p21.3. We aimed to investigate the possible role of 21-hydroxylase deficiency in linkage disequilibrium with HLA-B51 and causing androgen excess. Materials and Methods: We studied 18 healthy controls, 29 BD patients and 15 patients with ankylosing spondylitis (AS). All subjects underwent ACTH stimulation test. Basal and stimulated serum cortisol and 17-OH-progesterone (17-OH-P) levels and basal dehydroepiandrosterone sulfate (DHEA-S), total testosterone and sex hormone binding globulin (SHBG) levels were measured. Results: According to current guidelines, we accepted 10 ng/mL as the cut-off point for 17-OH-P to define non-classic CAH (NCAH). After ACTH stimulation 3 of BD patients (10.3%) and 5 AS patients (33.3%) had high 17-OH-P concentrations. Those individuals were considered as NCAH or possible carriers for CAH mutations. Three out of 8 BD patients with prominent acne were identified as NCAH biochemically. Mean total testosterone levels of BD patients were significantly lower than those of healthy controls, however these levels were normal in BD patients with high 17-OH-P. Conclusion: This preliminary work documented high 17-OH-P levels following ACTH stimulation in a subset of BD and AS patients, and genetic studies are necessary to investigate the role of 21-hydroxylase deficiency in association with HLA-B alleles in their pathogenesis. [ABSTRACT FROM AUTHOR]