17-alpha-hydroxylase/17,20 lyase deficiency

17-alpha-hydroxylase/17,20 lyase deficiency is a rare genetic condition caused by decreased or absent activity of the enzyme 17-alpha-hydroxylase/17,20 lyase, resulting from loss-of-function mutation(s) in the CYP17A1 gene. The clinical manifestations of this deficiency depend on whether one or both activities of the enzyme are affected.

Clinical Manifestations

The symptoms of 17-alpha-hydroxylase/17,20 lyase deficiency vary and may include:

• Hypertension: Caused by reduced 17-hydroxylase activity, leading to impaired cortisol and aldosterone metabolism.
• Incomplete genital masculinization in 46,XY infants: Due to reduced 17,20 lyase activity, which disrupts the production of androgens such as testosterone.

Genetics

The condition is associated with mutations in the CYP17A1 gene, which encodes the cytochrome P450 17A1 enzyme. This enzyme is essential for the synthesis of glucocorticoids, mineralocorticoids, and sex steroids. The severity of the condition depends on the specific mutation and its impact on enzyme activity.

Diagnosis

Diagnosis involves a combination of:

• Clinical evaluation of symptoms such as hypertension and atypical genital development.
• Hormonal testing to assess levels of cortisol, aldosterone, and sex steroids.
• Genetic testing to identify mutations in the CYP17A1 gene.

Management

Management of 17-alpha-hydroxylase/17,20 lyase deficiency is tailored to the specific symptoms and may include:

• Hormone replacement therapy (HRT): To address deficiencies in glucocorticoids, mineralocorticoids, or sex steroids.
• Antihypertensive therapy: To manage hypertension caused by impaired cortisol metabolism.
• Gender-affirming care: For individuals with incomplete genital masculinization, surgical and hormonal interventions may be considered.

Prognosis

With appropriate medical intervention, individuals with this condition can achieve a good quality of life. Early diagnosis and treatment are essential to manage the hormonal imbalances and associated complications.

NIH genetic and rare disease info

• NIH info on 17-alpha-hydroxylase/17,20 lyase deficiency

17-alpha-hydroxylase/17,20 lyase deficiency is a rare disease.

Template:Hormonal disorders

See Also

• CYP17A1
• Congenital adrenal hyperplasia
• Hormonal disorders
• Sex steroid biosynthesis