Located on chromosome 7, the CYP3A7 gene encodes an enzyme belonging to the cytochrome P450 family, sharing 87% of its sequence with CYP3A4. It carries out a similar role in fetuses that CYP3A4 serves in adults.Wikipedia
In 2019, a publication reported that the CYP3A7*1C allele of the gene was associated with increased etonogestrel metabolism in adult females, with 27.8% (5/18) of CYP3A7*1C carriers having serum etonogestrel concentrations too low to respond consistently to a contraceptive implant intended to invoke ovulatory suppression (less than 90 pg/mL).10.1097/AOG.0000000000003189
This was not the first report of a consequence in adults of carrying the CYP3A7*1C allele; other findings include:
- Lower (by 54%) urinary oestrone (E1) levels in premenopausal women, and a moderate increase in breast cancer mortality (HR, 1.74; p = 0.03), all-cause mortality in lung cancer patients (HR, 1.43; p = 0.009), and chronic lymphocytic leukemia (CLL) progression (HR, 1.62; p = 0.03).[PMID 26964624]
- Homozygous CYP3A7*1C carriers had significantly lower bone mineral density at the lumbar spine compared to wild types in a 2007 study based on 217 postmenopausal women with osteoporosis (and ~100 healthy women).[PMID 17334880]
The SNP that tags the CYP3A7*1C allele is rs45446698(C).