fundamentals
Genetic Diagnostic Technologies
Next generation sequencing technologies
Next-generation sequencing technologies can detect even smaller parts of genes and DNA by breaking the entire genotype (or genome) into small segments and then analyzing the DNA sequence of some or all of the segments. The results are then analyzed by a powerful computer. Single or multiple variations in bases may be identified as well as areas where bases are missing or have been inserted in the wrong place. The costs of this technology have dramatically fallen and continue to fall. The equipment and computational methods also continue to improve. Some of these variations can help doctors diagnose genetic disorders. Next-generation sequencing technologies are so sensitive that doctors can detect DNA from the fetus in a sample of blood drawn from the mother and analyze it to determine whether the fetus has Down syndrome. However, the sheer volume of information generated by analyzing the genotype results in a variety of problems that sometimes make it difficult for doctors to understand and interpret the results (for example, to distinguish important differences from random or trivial ones). Despite these issues, these techniques have become the mainstay of genetic testing. 