Definition of PGD and PGS

In general, preimplantation genetic diagnosis techniques can be divided into two large groups based on their purpose:

Preimplantation genetic diagnosis or PGD

is used to detect point mutations in the genetic material of embryos. These are usually mutations that cause serious inherited diseases, such as Fragile X syndrome, Huntington's disease, and muscular dystrophy.

Preimplantation genetic screening or PGS

also called screening for aneuploidies and consists of detecting alterations in the number or structure of chromosomes. The best known chromosomal disease is Down syndrome.