Case Report: Compound heterozygous mutation comprising p.Pro31Leu and exons 1-3 ins/del variants in CYP21A2 causes non-classical congenital adrenal hyperplasia in a Chinese girl.

Congenital adrenal hyperplasia (CAH) is caused by variants in the CYP21A2 gene and subsequently results in 21-hydroxylase deficiency. The non-classic form of CAH (NCCAH) often occurs in late puberty or in young adults due to a mild excess in postnatal androgen synthesis. This case report presents a case of a Chinese girl diagnosed with NCCAH. Clinical examinations and adrenal computed tomography were conducted in accordance with the standards and guidelines. Further genetic analysis was performed using PCR, next-generation sequencing, and multiplex ligation-dependent probe amplification. Clinical examinations demonstrated that the patient had amenorrhea, hyperandrogenism, insulin resistance, adrenal hyperplasia, and a masculine vulva, while polycystic ovary syndrome was excluded. Genetic analysis identified a compound heterozygous mutation comprising the c.92C>T p.Pro31Leu and exons 1-3 del variants in the CYP21A2 gene, while the exons 1-3 ins/del variant mainly caused the lack of CYP21A2 function. Herein, we report a Chinese girl with NCCAH due to a heterozygous mutation comprising the p.Pro31Leu and exons 1-3 ins/del variants in CYP21A2.