CYP21A2 intronic variants causing 21-hydroxylase deficiency.

Area of Science:

• Genetics
• Endocrinology
• Molecular Biology

Background:

• Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders.
• Defects in the steroid 21-hydroxylase gene (CYP21A2) are the primary cause of CAH.
• Most CYP21A2 mutations arise from recombination with the CYP21A1P pseudogene, but rare intronic variants also cause disease.

Purpose of the Study:

• To conduct a comprehensive literature review of all reported intronic CYP21A2 pathological variants.
• To identify and characterize novel intronic variants in patients with classic CAH.
• To analyze the impact of these variants on protein function and splicing.

Main Methods:

• Literature search for intronic CYP21A2 variants.
• Genetic analysis of patients with classic CAH.
• In silico analysis to predict the effect of variants on splicing.

Main Results:

• A comprehensive review of intronic CYP21A2 variants was compiled.
• Three novel intronic variants (IVS4-1G>A, IVS5-8T>A, IVS8-2A>G) were identified in patients with classic CAH.
• In silico analysis indicated that these novel variants disrupt the splicing process, leading to non-functional CYP21A2 protein.

Conclusions:

• Intronic variants in CYP21A2 are a significant, though less common, cause of 21-hydroxylase deficiency.
• The identified novel variants are pathogenic and contribute to the development of classic CAH.
• These findings underscore the importance of evaluating intronic regions for mutations in diagnosing CAH.