There are 3 forms of PGT: PGT-M: Testing for monogenic (ie, single-gene) abnormalities PGT-A: Testing for aneuploidy PGT-SR: Testing for structural rearrangements such as unbalanced translocations PGT-M is used primarily for couples when the risk of certain mendelian disorders (eg, cystic fibrosis) in the fetus is high.