Context: Polycystic ovary syndrome (PCOS) theca. cells secrete increased levels of androgens. The mRNA and protein levels of the transcription factor GATA6, which regulates expression of several steroidogenic enzymes are increased in PCOS theca cells. Thus, GATA6 is a PCOS candidate gene. Objective: Explore mechanisms by which GATA6 mRNA levels are increased in PCOS theca cells. Design: Theca cell cDNA and genomic DNA from normal individuals and PCOS patients were subjected to quantitative RT-PCR and sequence analysis, respectively. Setting: University laboratory. Participants: 469 families which contain at least one PCOS patient were ascertained for genetic studies. Theca cells were obtained from 4 normal individuals and 4 PCOS patients. Results: Nascent GATA6 transcript levels, which reflect GATA6 gene transcription, were significantly increased in PCOS theca cells. In normal theca cells, GATA6 mRNA has a short half-life which was attributed to an AU-rich 3'-UTR sequence. The half-life of GATA6 transcripts was also significantly longer in the PCOS theca cells. However, no sequence variations in the GATA6 gene locus were associated with PCOS. Conclusions: In PCOS theca cells, GATA6 gene transcription and the stability of the GATA6 mRNA are increased. Since there is no sequence variation in the GATA6 gene locus which is associated with PCOS, it is likely that the increased gene transcription and mRNA stability are due to intrinsic differences in PCOS theca cells.