Traditional PGD for single gene mutation requires a DNA probe custom made for the specific genetic mutation carried by an affected individual or couple. A blood or buccal membrane sample must be obtained from the couple planning to have IVF and PGD. It takes 12-16 weeks for the customized DNA test development.
A newer technique in PGD is called karyomapping. It tests just a couple of weeks, not months, for test development and allows a universal test for PGD of almost any genetic mutation. Essentially karyomapping finds a fingerprint that is unique to the chromosome that carries the defective gene. The embryos are tested for this presence of this fingerprint. Whenever the fingerprint is seen in an embryo it means it has inherited the chromosome carrying the defective gene.
Often PGD is done along with PGS for chromosomal aneuploidy, selecting an embryo with a normal set of chromosome AND without the known genetic mutation.