Related Experiment Video
Updated: Jan 4, 2026

In Vitro Enzyme Measurement to Test Pharmacological Chaperone Responsiveness in Fabry and Pompe Disease
Published on: December 20, 2017
A rare enzymatic defect, true isolated 17,20-lyase deficiency leading to endocrine disorders and infertility: case
Jamileh Afsar1, Ali Kachuei1, Mahin Hashemipour2
1Department of Internal Medicine, School of Medicine, Al-Zahra Hospital, Isfahan Endocrine and Metabolism Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
Abstract:
The cytochrome P450 17A1 catalyzes the formation of 17-hydroxysteroids and 17-ketosteroid. Most defects in CYP17A1 impair both enzymatic activities and cause a combined 17α-hydroxylase/17,20-lyase deficiency, which impairs hormone production (cortisol and sex steroids), sexual development, and puberty. Isolated 17,20-lyase deficiency is usually defined by evidently normal activity of 17α-hydroxylase with a dramatic decline of 17,20-lyase activity or complete inactivity. The changes in enzyme activity lead to a lack in the production of sex steroids with normal levels of glucocorticoid and mineralocorticoid hormones. A 24-years-old married woman, as a product of a consanguineous marriage, presented with infertility and a background marked by primary amenorrhea. Laboratory data showed low normal serum cortisol levels and low levels of 17-hydroxyprogesterone. Also, her adrenal androgens were low but estradiol was normal. The chromosomal investigation uncovered a male karyotype of 46, XY. These clinical and laboratory evidence confirm the determination of an isolated 17,20-lyase deficiency in a genotypic male.
Related Concept Videos
Inborn Errors of Metabolism
Lysosomal Hydrolases
Sex-linked Disorders
Smooth Endoplasmic Reticulum
The ER provides optimal conditions for synthesizing steroid hormones and lipids, such as phospholipids and triglycerides. Traditionally, lipid metabolism was considered to be a smooth ER function. However, there is no direct evidence to prove that rough ER is completely excluded from lipid...
Overview of Protein Metabolism
Amino acids play various roles in the body once they are absorbed into cells. They are restructured...
Glucose Transporters
Facilitated diffusion-glucose transporters (GLUTs) are encoded by the solute-linked carrier (SLC) family 2, subfamily A gene family, or SLC2A. The 14 GLUT protein members are distributed into three classes:

