Preimplantation genetic diagnosis for BRCA1 exon 13 duplication mutation using linked polymorphic markers resulting in a live birth

Abstract

The risk of breast cancer associated with inheriting a BRCA1 mutation is extremely high, in addition, there is a 50% chance of transmitting this familial cancer mutation to any offspring. A 31-year-old woman with a strong maternal family history of early onset of breast cancer had experienced 3 years of primary infertility. Presymptomatic testing confirmed the woman had inherited a 6 kb duplication of exon 13 (ins6KbEx13) in BRCA1 from her mother. Neither gamete donation or adoption were acceptable options for this infertile couple, and as termination of pregnancy after prenatal diagnosis following in vitro fertilization (IVF) was not ethically acceptable, preimplantation genetic diagnosis (PGD) was sought. A single-cell PCR protocol for PGD for the breast and ovarian cancer predisposing BRCA1 exon 13 duplication mutation was developed which involved amplification of three specific gene regions, including the BRCA1 mutation (ins6KbEx13), an intragenic marker (D17S855) and a flanking marker (D17S1185). In the first cycle of IVF, three embryos were analyzed and two were determined to be at low risk of having inherited the maternal BRCA1 mutation. Following the transfer of both embryos on day 5, a singleton pregnancy resulted. Declining confirmatory prenatal diagnosis, a male baby was subsequently delivered at term. Successful PGD for BRCA1 resulted in the delivery of a live-born male. PGD using linked polymorphic markers provides an alternate option for reproduction for couples with or at risk of having inherited a BRCA1 mutation.