The cause of hereditary diseases is a pathogenic changes in the genetic material. This changes are necessary and sufficient to cause the monogenic disease. Determining specific change has caused the disease in an individual patient is the basis for modern medical genetics and genetic counseling. This allows us to determine the best course of treatment, the rise of recurrence in the family, and to plan preconception prevention and prenatal diagnosis. It also basis design of pathogenetic/etiotropic therapy. Geneticists have a wide range of tools at their disposal to study nucleic acids. These include polymerase chain reaction (PCR) and its variations, as well as Multiplex Ligation-dependent Probe Amplification and various methods for sequencing nucleotide sequences: from Sanger sequencing for single gene to whole genome sequencing.
Polyakov et al. (Wed,) studied this question.