[Failure of mifepristone induced interruption of pregnancy: point mutation at genetic codon 722 in human progesterone receptor gene].

OBJECTIVE

To detect the point mutation of hormone binding domain (HBD) of human progesterone receptor (hPR) gene by molecular biological methods in women with insensitivity to mifepristone.

METHODS

26 women in 5 hospitals were consented in the study. 16 women were as study group: continuing pregnancy in 11 and missed abortion in 5. 10 women with successful abortion were as control group. Decidual tissue was collected in each woman and RNA was extracted from it and purified. Reverse transcription-polymerase chain reaction (RT-PCR), single strand conformation polymorphism(SSCP) and restriction enzyme reaction were performed. All women were followed up.

RESULT: No point mutation of HBD of hPR gene was detected in control group except one with point mutation in trace. Point mutation of HBD of hPR gene was detected in 7 of women with continuing pregnancy. Mifepristone was administrated in midluteal phase in two of these women and no vaginal bleeding was observed. No mutation of hPR gene in the other women with continuing pregnancy. Three women had pregnancy again in 6 months and had successful abortion. The other one administrated mifepristion in midluteal phase and had second vaginal bleeding. No point mutation of hPR gene was detected in women with missed abortion.

CONCLUSION

There is point mutation of HBD of hPR gene in women with insensitivity to mifepristone, and women with point mutation of hPR gene detected by molecular biological methods are really insensitive to mifepristone.