PHENOTYPE: This locus controls activity in liver of females of a 16alpha-hydroxylase with high affinity for testosterone and progesterone and low affinity for pregnenolone. 129/J carries the low activity allele; C57BL/6, DBA/2, AKR, C3H/I and BALB/c the high activity allele. Heterozygotes are intermediate. [provided by MGI curators]