ESPE Abstracts

Purpose: Identify CYP21A2 gene variants in pediatric patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency from Henan, China, and to analyze genotype-phenotype correlations. We also analyze the relationship between the clinically effective dosage of hydrocortisone and CYP21A2 genotype.

Materials/Methods:A total of 214 21-OHD children were recruited in Henan children's hospital from 2008 to 2023. The patients were categorized into five genotypic groups（group 0, group A, group B, group C and group D) according to their residual CYP21A2 enzymatic activities. The expected phenotype associated with groups 0 or A was salt-wasting (SW) form. Genotype of patients in group B were predicted to result in simple virilizing (SV) form and those of group C were predicted to present as non-classic (NC) form. The dosage of hydrocortisone was calculated for each genotype group at the age of 1 year and 6 years, respectively (including 153 cases aged 1 year and 92 cases aged 6 years), and analyzed whether there is statistically significant difference in the dosage of hydrocortisone among the groups.

Results: In this study, 214 children were diagnosed with 21-OHD, among whom 161 (75.2%) presented SW form, 48 (22.4%) presented SV form and 5 (2.3%) presented NC form. The most frequent micro-conversion was I2G (35.0%), p.I173N (12.0%), p.Q319* (6.1%), p.R357W (5.6%). Other 25 different types of spontaneous mutations accounted for 8.4% of alleles. Large gene deletions account for 19.7%. Among 214 patients, 8 cases had spontaneous mutations in one allele, while the mutation in the other allele was inherited from the father or mother. In 214 patients genotype-phenotype correlations measured by positive predictive value (PPV) were as follows: 92.6% in group 0, 93% in group A, 68% in group B，and 50% in group C. Among 153 children aged 1 year or older, the average dosage of hydrocortisone in Group 0, A, B, and C was 10.33±2.38mg/m2,10.38±2.56mg/m2,11.51±2.59mg/m2,10.56±2.48mg/m2 respectively. Among 92 children aged 6 years or older, the average dosage of hydrocortisone in group 0, A, B, and C was 11.7±2.47mg/m2,11.48±2.58mg/m2,11.68±2.62mg/m2,11.4±2.59mg/m2 respectively, There is no statistical difference among the groups.

Conclusions: There was a good correlation between genotype and phenotype in group 0 and group A, while the correlation is considerably lower in group B and C. There is no statistical difference between the clinically effective dosage of hydrocortisone and genotype group.