Preimplantation genetic testing for Huntington disease: the perspective of one Portuguese center

BACKGROUND: Huntington disease (HD) is an autosomal dominant late-onset neurodegenerative disease caused by an unstable cytosine-adenine-guanine trinucleotide repeat expansion in the huntingtin (HTT) gene. Preimplantation genetic testing (PGT) is a diagnostic procedure available for these individuals, because they carry a high risk of transmitting this genetic condition to their offspring. METHODS: Information about 15 HD couples referred for PGT and 21 cycles performed from 2009 to 2018 was collected retrospectively. PGT provide direct testing of embryos obtained after intracytoplasmic sperm injection, using polymerase chain reaction multiplex as the genetic testing protocol. RESULTS: PGT for HD was performed in 15 couples, with no history of previous attempts, in a total of 21 cycles. The mean number of biopsied embryos per cycle was 4.9. The amplification efficiency in blastomeres was 87.4%. From the 90 amplified embryos, 32 were normal and suitable for transfer. The mean number of transferred embryos per couple was 1.2. Overall, 3 positive human chorionic gonadotropin tests were obtained in 3 couples, resulting in 2 clinical pregnancies. The 2 ongoing clinical pregnancies had normal evolution, and culminated in 2 deliveries, resulting in the birth of 2 healthy children. CONCLUSIONS: PGT for HD is considered an effective and safe reproductive option for couples who are at risk of transmitting HD, when proper genetic and reproductive counseling is warranted.