[Genetic analysis of a case with 11β hydroxylase deficiency caused by CYP11B2/CYP11B1 chimeric gene].

Objective: To analyze a child with 11β hydroxylase deficiency (11β-OHD) due to CYP11B2/CYP11B1 chimeric gene.
Methods: Clinical data of the child who was admitted to Henan Children's Hospital on August 24, 2020 were retrospectively analyzed. Peripheral blood samples of the child and his parents were collected and subjected to whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing. RT-PCR and Long-PCR were carried out to verify the presence of chimeric gene.
Results: The patient, a 5-year-old male, had featured premature development of secondary sex characteristics and accelerated growth, and was diagnosed with 21 hydroxylase deficiency (21-OHD). WES revealed that he has harbored a heterozygous c.1385T>C (p.L462P) variant of the CYP11B1 gene, in addition to a 37.02 kb deletion on 8q24.3. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c.1385T>C (p.L462P) was rated as a likely pathogenic variant (PM2_Supporting+PP3_Moderate+PM3+PP4). The results of RT-PCR and Long-PCR suggested that CYP11B1 and CYP11B2 genes have recombined to form a CYP11B2 exon 1~7/CYP11B1 exon 7~9 chimeric gene. The patient was diagnosed as 11β-OHD and effectively treated with hydrocortisone and triptorelin. A healthy fetus was delivered following genetic counseling and prenatal diagnosis.
Conclusion: 11β-OHD may be misdiagnosed as 21-OHD due to the potential CYP11B2/CYP11B1 chimeric gene, which will require multiple methods for the detection.