Characterisation of three novel CYP11B1 mutations in classic and non-classic 11β-hydroxylase deficiency

Abstract

BackgroundCongenital adrenal hyperplasia (CAH) is one of the most common autosomal recessive inherited endocrine diseases. Steroid 11β-hydroxylase (P450c11) deficiency (11OHD) is the second most common form of CAH.AimThe aim of the study was to study the functional consequences of three novelCYP11B1gene mutations (p.His125Thrfs*8, p.Leu463_Leu464dup and p.Ser150Leu) detected in patients suffering from 11OHD and to correlate this data with the clinical phenotype.MethodsFunctional analyses were done by using a HEK293 cellin vitroexpression system comparing WT with mutant P450c11 activity. Mutant proteins were examinedin silicoto study their effect on the three-dimensional structure of the protein.ResultsTwo mutations (p.His125Thrfs*8 and p.Leu463_Leu464dup) detected in patients with classic 11OHD showed a complete loss of P450c11 activity. The mutation (p.Ser150Leu) detected in a patient with non-classic 11OHD showed partial functional impairment with 19% of WT activity.ConclusionFunctional mutation analysis enables the correlation of novelCYP11B1mutations to the classic and non-classic 11OHD phenotype respectively. Mutations causing a non-classic phenotype show typically partial impairment due to reduced maximum reaction velocity comparable with non-classic mutations in 21-hydroxylase deficiency. The increasing number of mutations associated with non-classic 11OHD illustrate that this disease should be considered as diagnosis in patients with otherwise unexplained hyperandrogenism.