Novel homozygous p.Y395X mutation in the CYP11B1 gene found in a Vietnamese patient with 11β-hydroxylase deficiency.

Context: The deficiency of steroid 11β-hydroxylase is caused by mutations in the CYP11B1 gene and is the second major form of congenital adrenal hyperplasia associated with hypertension.

Objective: The objective of this study was to screen the CYP11B1 gene for mutations in one Vietnamese male suffering from congenital adrenal hyperplasia.

Patient: The patient (46,XY) had congenital adrenal hyperplasia. The clinical manifestations presented precocious puberty, hyper-pigmentation and high blood pressure at 4 years.

Results: The patient was a homozygous carrier of a novel mutation located in exon 7 containing a premature stop codon instead of tyrosine at 395 (p.Y395X).

Conclusion: We have identified a novel mutant of the CYP11B1 gene in one Vietnamese family associated with phenotypes of congenital adrenal hyperplasia. The mutant gene p.Y395X produces a truncated form of the polypeptide and abolishes the enzyme activities, leading to a severe phenotype of congenital adrenal hyperplasia.