Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is a complicated condition genetically, clinically, and treatment wise. Genetically, there are numerus mutations with different effect on enzyme activity that make genetic diagnosis a challenge. Clinically, there are a wide range of presentations from asymptomatic patients to the severe life-threatening classic CAH. Both an asymptomatic heterozygote and a mildly affected non-classical patient can carry a ‘severe’ mutation and endow it to their offspring. We present a case of non-classic CAH and discuss the problematic relations between biochemical and genetic diagnosis. By integrating the seemingly contradicting literature, we provide a new simple tool to assess the risk of such patients to give birth to a child with classic CAH.

由 21-羟化酶缺乏引起的先天性肾上腺增生 (CAH) 在遗传、临床和治疗方面都是一种复杂的疾病。在遗传上，存在许多对酶活性具有不同影响的突变，这使基因诊断成为一项挑战。临床上，从无症状患者到严重危及生命的经典 CAH 的表现范围很广。无症状杂合子和轻度受影响的非经典患者都可以携带“严重”突变并将其赋予后代。我们介绍了一个非经典 CAH 病例，并讨论了生化诊断与基因诊断之间存在问题的关系。通过整合看似矛盾的文献，我们提供了一种新的简单工具来评估此类患者生下经典 CAH 孩子的风险。