Background: CYP21A2 gene mutations may all cause reduction or loss of 21-hydroxylase activity, leading to development of congenital adrenal hyperplasia (CAH) with different clinical phenotypes. For families with CAH children, genetic testing of the parents and genetic counseling are recommended to assess the risk of recurrence.
Case summary: We report a case of CAH with a high suspicion before delivery. The risk of the child suffering from CAH during the pregnancy had been underestimated due to the deviation of genetic counseling and genetic testing results. Our report confirmed a CYP21A2 homozygous deletion in this case, CYP21A2 heterozygous deletion in the mother, and a rare 2+0 CYP21A2 deletion in the father.
Conclusion: It is important to analyze the distribution of CYP21A2 gene in the two alleles of parents of children with CAH.
Keywords: Alleles; CYP21A2 gene mutations; Congenital adrenal hyperplasia; Genetic counseling; Genetic testing; Pathogenic point mutations; Pregnancy.
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