 It has become increasingly popular because it grants individuals the option of detecting embryo abnormalities before implantation, rather than during the beginning weeks of pregnancy.The latter often results in embryo abortion, presenting an ethical dilemma for many that can now be avoided.PGH uses information regarding family history in conjunction with the use of linked polymorphic markers such as short tandem repeats (STRs) and single nucleotide polymorphisms (SNPs) to locate genes responsible for disease.