{{Rsnum
|rsid=7769409
|Chromosome=6
|Orientation=plus
|geno1=(C;C)
|geno2=(C;T)
|geno3=(T;T)
|Gene=C4B
|position=32040535
|Assembly=GRCh38
|GenomeBuild=38.1
|dbSNPBuild=141
|Gene_s=CYP21A2
}}
90% of all [[Polycystic ovary syndrome]] (PCOS), the most common cause {{PMID|18844715}} cases are caused by a heterozygous mutation of gene [[CYP21A1]].

Variations in [[CYP11B1]] is a second reason for developing [[hyperandrogenism]].


{{omim
|id=201910
|rsnum=7769409
|variant=0003
}}{{ClinVar
|rsid=7769409
|Reversed=0
|FwdREF=C
|FwdALT=T
|REF=C
|ALT=T
|RSPOS=32008312
|CHROM=6
|dbSNPBuildID=116
|SSR=1
|SAO=1
|VP=0x050260000000070102110100
|GENEINFO=CYP21A2:1589
|GENE_NAME=CYP21A2
|GENE_ID=1589
|WGT=0
|VC=SNV
|CLNALLE=1
|CLNHGVS=NC_000006.11:g.32008312C>T
|CLNORIGIN=1
|CLNSIG=5
|Tags=PM;S3D;VLD;G5A;G5;GNO;OTHERKG;LSD;OM
|CLNACC=RCV000012937.2
|CLNDBN=21-hydroxylase deficiency
|CLNSRC=GeneReviews; OMIM Allelic Variant
|CLNSRCID=NBK1171; 613815.0003
|Disease=21-hydroxylase deficiency
|CLNDSDB=GeneReviews:MedGen:OMIM
|CLNDSDBID=NBK1171:C0852654:201910
}}