Genotype-Phenotype Correlation and Feminizing Surgery in Danish Children with Congenital Adrenal Hyperplasia

Introduction: Congenital adrenal hyperplasia (CAH) is characterized by a broad spectrum of symptoms. This study aimed to describe genotype-phenotype correlations, clinical manifestations at diagnosis, and the frequency of feminizing surgery in childhood. Methods: A nationwide retrospective cohort study of patients diagnosed with CAH, at the age of =18 years, between 1943 and 2018. CAH was identified in national registries and validated through medical record reviews and phenotypically classified as salt-wasting (SW), simple virilizing (SV), or non-classic (NC) CAH. In a sub-cohort (diagnosed between 1999 and 2018), clinical data and feminizing surgery data were investigated. CYP21A2 variants were grouped as Null, A, B, C, and D. Results: The cohort comprised 379 patients with CAH. Genotype-phenotype correlations were as follows: Null and SW (100%), A and SW (94%), B and SV (51%), and C and NC (75%). In the subcohort (n = 159, females = 99), the female-to-male ratios were SW = 1.5, SV = 1.1, and NC = 2.3. Symptoms of precocious pseudopuberty dominated at diagnosis (39%). Males presented with significantly advanced bone age by the time of diagnosis (p = 0.0009). In 53% of females (n = 53), virilization of the external genitalia was present at the time of diagnosis, and in 46% (n = 46), this already developed prenatally. Of the prenatal virilized females, 85% underwent early feminizing genitoplasty. Virilization was identified in both mild and severe genotypes. Conclusion: Milder genotypes do not accurately predict CAH phenotype or prenatally reject serious outcomes such as virilization. The frequency of early genitoplasty is high among females with prenatal virilization. The delayed diagnosis and nondiagnosis of especially males with mild CAH advocate for a more prominent role of genetic testing in the diagnostic and screening for CAH.