摘要患儿因“生后发现外生殖器畸形26 d”于中南大学湘雅二医院就诊，通过多重连接探针扩增+Sanger测序及全基因组测序对患儿及其父母进行基因检测，发现患儿存在 CYP21A2基因复合杂合变异。因具体变异位点不详，通过三代基因测序技术中的单分子实时测序检出患儿存在 CYP21A1P/ CYP21A2融合基因嵌合体-8型变异与c.332_339del的复合杂合变异。基因型与表型相符，患儿确诊为失盐型21-羟化酶缺陷症，给予氢化可的松及氟氢可的松替代治疗，病情得到有效控制。患儿8月龄行矫正外生殖器外观手术，预后良好。

abstractsA female infant with ambiguous genitalia, identified at 26 days postnatal, was admitted to the Second Xiangya Hospital, Central South University. Genetic testing was performed on the child's pedigree using multiplex ligation-dependent probe amplification, Sanger sequencing, and whole genome sequencing, which revealed a compound heterozygous variation in the CYP21A2 gene. The specific mutation sites were indeterminate, and third-generation gene sequencing technology, single- molecule real-time sequencing, subsequently identified a chimera-8 type variant of CYP21A1P/CYP21A2 fusion gene and a c.332_339del compound heterozygous variation in the infant. The genotype matched the phenotype, leading to a diagnosis of salt-wasting 21-hydroxylase deficiency, a rare genetic disorder. The infant was treated with hydrocortisone and fludrocortisone replacement therapy, which effectively controlled the condition. At 8 months old, the infant underwent surgery to correct the appearance of the external genitalia, with a favorable prognosis.