Dual Heterozygous Mutations in CYP21A2 and CYP11B1 in a Case of Nonclassic Congenital Adrenal Hyperplasia

Congenital Adrenal Hyperplasia with Combined 21-hydroxylase deficiency and 17α-hydroxylase/17,20-lyase deficiency: An undervirilized male

21-hydroxylase deficiency stands as the most prevalent form of congenital adrenal hyperplasia, primarily resulting from mutations in the CYP21A2 gene. On the other hand, mutations within the CYP17A1 gene lead to 17α-hydroxylase/17,20-lyase enzyme deficiencies. The scarcity of 17-OH deficiency is noteworthy, accounting for less than 1% of all congenital adrenal hyperplasia cases. The male patient, born from a first-degree cousin marriage, exhibited several symptoms, including left undescended testis, micropenis, penile chord, left sensorineural hearing loss, and gynecomastia. He reported micropenis as a concern at the age of 13.5 years. His hormone profile revealed high levels of serum 17-hydroxyprogesterone, progesterone, and pregnenolone. In this case with a 46 XY karyotype, suspicions arose regarding Cytochrome P450 oxidoreductase deficiency due to ambiguous genitalia and an atypical hormone profile. Analysis unveiled two distinct homozygous and pathogenic variants in the CYP21A2 and CYP17A1 genes. Notably, mineralocorticoid precursors escalated, while cortisol and sex steroid precursors decreased during the high (250 mcg) dose ACTH stimulation test. The mutation c.1169C > G (p.Thr390Arg) in CYP17A1, which is the second documented case in literature, stands out due to its unique set of accompanying features. Mutations occurring in CYP21A2 and CYP17A1 result in complete or partial enzyme deficiencies, and the detection of homozygous mutations in two different enzyme systems within the steroidogenic pathway is noteworthy.