Molecular testing on fetal DNA to test directly for specific mutations or to assess closely linked markers for an unknown mutation
Use
To assess mutational status for specific inherited diseases
Typically performed only when parents are affected or known carriers for disease
Limitations
Direct testing assesses only particular targeted mutation(s) of interest
Linkage analysis, testing of a nearby genetic marker used when the particular mutation is unknown, is limited by potential recombination between the tested marker and the causal mutation.
Mitochondrial DNA testing may be problematic because the mutated mitochondrial mutation is likely to exist in combination with normal mitochondria (heteroplasmy).