Gene Information
Gene Symbol
CPT7, CYP17, P450C17, S17AH
Entrez Gene ID
Gene Name
Cytochrome P450 family 17 subfamily A member 1
Chromosomal Location
This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. This protein localizes to the endoplasmic reticulum. It has both 17alpha-hydroxylase and 17,20-lyase activities and is a key enzyme in the steroidogenic pathway that produces progestins, mineralocorticoids, glucocorticoids, androgens, and estrogens. Mutations in this gene are associated with isolated steroid-17 alpha-hydroxylase deficiency, 17-alpha-hydroxylase/17,20-lyase deficiency, pseudohermaphroditism, and adrenal hyperplasia. [provided by RefSeq, Jul 2008]
RefSeq DNA
RefSeq mRNA

Gene Ontology (GO)

GO ID Ontology Function Evidence Reference
GO:0006694 Biological process Steroid biosynthetic process TAS 3500022
GO:0007548 Biological process Sex differentiation TAS 9326943
GO:0008202 Biological process Steroid metabolic process IDA 22266943
GO:0042446 Biological process Hormone biosynthetic process IBA 21873635
GO:0042446 Biological process Hormone biosynthetic process IDA 22266943
Protein Information
Protein Name
Steroid 17-alpha-hydroxylase/17,20 lyase, 17-alpha-hydroxyprogesterone aldolase, CYPXVII, cytochrome P450 17A1, cytochrome P450, family 17, subfamily A, polypeptide 1, cytochrome P450, subfamily XVII (steroid 17-alpha-hydroxylase), adrenal hyperplasia, cytochrome P450-C17, cytochrome P450c17, cytochrome p450 XVIIA1, steroid 17-alpha-monooxygenase
A cytochrome P450 monooxygenase involved in corticoid and androgen biosynthesis. Catalyzes 17-alpha hydroxylation of C21 steroids, which is common for both pathways. A second oxidative step, required only for androgen synthesis, involves an acyl-carbon cleavage. The 17-alpha hydroxy intermediates, as part of adrenal glucocorticoids biosynthesis pathway, are precursors of cortisol(Probable). Hydroxylates steroid hormones, pregnenolone and progesterone to form 17-alpha hydroxy metabolites, followed by the cleavage of the C17-C20 bond to form C19 steroids, dehydroepiandrosterone (DHEA) and androstenedione . Has 16-alpha hydroxylase activity. Catalyzes 16-alpha hydroxylation of 17-alpha hydroxy pregnenolone, followed by the cleavage of the C17-C20 bond to form 16-alpha-hydroxy DHEA. Also 16-alpha hydroxylates androgens, relevant for estriol synthesis. Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate, and reducing the second into a water molecule, with two electrons provided by NADPH via cytochrome P450 reductase (CPR; NADPH-ferrihemoprotein reductase)
Refseq Proteins
Pfam Accession Pfam ID
PF00067 p450

Steroid hormone biosynthesis
Metabolic pathways
Ovarian steroidogenesis
Prolactin signaling pathway
Cortisol synthesis and secretion
Cushing syndrome


Androgen biosynthesis
Glucocorticoid biosynthesis
Defective CYP17A1 causes Adrenal hyperplasia 5 (AH5)

ENSP00000222381 P27169
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Associated Diseases

Disease groupDisease NameReferences
Cardiovascular Diseases
Coronary heart disease
Malignant Hypertension
Myocardial Infarction
Digestive System Diseases
Non-alcoholic Fatty Liver Disease
Endocrine System Diseases
17,20-Lyase Deficiency
PubMed ID Associated gene/s Associated condition Genetic Mutation Diagnostic Criteria Association with PCOS Ethnicity Conclusion
216- allele 
123 (65 PCOS, 58 controls) 
The results suggest that both alleles play a minor role in the development of PCOS and could be a genetic risk marker of the hyperandrogenic phenotype 
CYP11A1,androstenedione,17alpha-hydroxyprogesterone, and DHEAS 
Polymorphism in CYP17 promoter 
Rotterdam criteria 
India-100 PCOS and 100 controls 
The study carried out in a defined group of Indian women with PCOS suggests for the first time an individual, as well as combined, association of polymorphisms in CYP11A1 and CYP17 promoters with T levels. 
Variant in gene 
134 Korean women with PCOS and 100 healthy women as controls 
The frequency of seven SNPs had no significant association with PCOS. However, one haplotype (ht3) had a p-value of p=0.001, suggesting that it may be associated with the pathogenesis of PCOS in a Korean population. 
NICHD criteria 
259 consecutive unselected white patients with PCOS and 161 control  
It does not appear that this common variant of CYP17, a T to C substitution in the 5' promoter region, plays a significant role in the adrenal androgen excess of PCOS. 
Activity of CYP17 and CYP11A, was increased in the PCOS compared to normal theca cells 

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