<unk>  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. Both STRs and SNPs are variations in gene nucleotides, and it is estimated that there are tens of millions of each type of variation in human DNA. High frequency of STRs or SNPs in alleles of affected individuals in comparison to their unaffected direct relatives indicates the origin of a disease causing mutation. They thus "mark" alleles as having a mutation without having to specifically identify the mutation. Because the number of potential STRs and SNPs is so high, a family pedigree helps to narrow the scope of alleles to analyze. Further, understanding how the gene of interest gets expressed over time helps ultimately determine which haplotype is responsible for the alleles linked to the mutation. A haplotype map is thus created, not only exhibiting genes the offspring will contain, but also the parental origin of the genes. Once the alleles that correlate with a mutation are characterized,<unk>  of the embryos is possible and only embryos carrying the low risk haplotypes are selected for transfer.<unk>  is performed in vitro until this point, when the chosen embryos get placed in the uterus of a surrogate mother for further development.
Preimplantation genetic haplotyping
Preimplantation genetic diagnosis
Non invasive prenatal testing
Pre-conception counseling
Genetic diagnosis of intersex
Genetic counseling
Genomic counseling
Fetal echocardiography