`When lightning strikes twice` - PGD for two genetic diseases in one sample

Objectives: PGD was proven to be a powerful tool to prevent genetic diseases. PGD can be also used to select against multiple genetic disorders that are present in the same family. These types of PGD cycles are a great challenge as the final total embryos suitable for transfer may be substantially lower.

Aim: to identify the success rate of PGD for multiple genetic disorders in a single embryo.

Methods: a retrospective cohort surveying patients that underwent PGD for two or more genetic indications at Hadassah-Hebrew-University hospital between the years 2005 to 2016. Data collected included patient characteristics, genetic indications, number of IVF cycles, number of embryos sampled, number of embryos transferred, implantation rate and pregnancy rate, method of genetic diagnosis and live birth rate.

Results: 859 couples underwent PGD for various indications. Fifteen couples (2%) had more than one genetic indication. Multiple indications are listed in table 1. Twelve couples (80%) eventually underwent 40 IVF-PGD cycles in total (mean 3.3±SD cycles per couple). Of these, 257 embryos were sampled (mean 21.4±SD per couple) with mean 6.4±SD embryos sampled per cycle. Forty two fetuses were suitable for ET. The post PGD mean no. of embryos suitable for transfer was 1.3±1.3 and the mean no. of embryos transferred was 1±0.91. The implantation rate was 38.4% and clinical pregnancy rate 42%. So far, we documented 7 live births (5 singletons and 1 pair of twins). Two pregnancies are still ongoing.

Conclusions: The PGD technique is complicated when more than one genetic disease are to be tested within the same embryo. Although lower numbers of embryos qualified for transfer, the clinical pregnancy rate per cycle, is comparable with PGD testing for a single disease.