Timely diagnosis of recessive single-gene diseases in patients is of the utmost importance for the implementation of the available methods of disease prevention or specific symptomatic therapy when the disease has already developed. Furthermore, an important link in the prevention and monitoring of the likelihood of appearance of recessive monogenic diseases are various possibilities of genetic testing that can detect carriers, who are most often healthy individuals but can transmit the genetic change to offspring. This review article presents the latest findings related to the definition, frequency, and diagnosis of recessive monogenic diseases, including diagnostic genetic testing, carrier testing, population screening, and extended genomic carrier screening. [ABSTRACT FROM AUTHOR]