What is the essence of cytogenetic and biochemical methods for studying human genetics. For what purpose are they used in medicine?

The cytogenetic method is used to study the normal human karyotype, as well as in the diagnosis of hereditary diseases associated with genomic and chromosomal mutations.
Biochemical method. This method is used to diagnose metabolic diseases caused by changes in the activity of certain enzymes. Using the biochemical method, about 500 molecular diseases are discovered that are the result of the manifestation of mutant genes. This method is very laborious, requires special equipment and therefore cannot be widely used for mass population studies with the aim of early detection of patients with hereditary metabolic pathology.
In medicine, these methods are used to create drugs.

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