DNA Microarrays: The Applications and Its Future Prospect

Posted by beauty33 on November 15th, 2021

Mutations or changes in the DNA of specific genes may cause certain diseases. However, developing tests to detect these mutations can be very difficult because most large genes have many regions where mutations can occur. DNA microarray is a tool used to determine whether a specific individual\'s DNA contains genetic mutations such as BRCA1 and BRCA2.

Initially, DNA microarrays were only used as research tools. Now, however, DNA microarrays can be used to determine how often individuals with specific mutations actually have breast cancer, or to determine the changes in the gene sequence most commonly associated with specific diseases. DNA microarrays can also be used to study the degree to which certain genes are turned on or off in cells and tissues. In this case, instead of separating DNA from the sample, RNA is separated and measured.

Nowadays, DNA microarrays are used in clinical diagnostic tests for certain diseases, and sometimes they are also used to determine which drugs are best for specific individuals, because genes determine how our body processes the chemical reactions associated with these drugs. With the advent of new DNA sequencing technologies, some of the tests used by microarrays have been used in the past and now to use DNA sequencing instead. But microarray tests are still cheaper than sequencing, so they can be used for very large studies as well as some clinical tests.

Microarrays are simply devices that measure the relative concentration of many different DNA or RNA sequences at the same time. Although they are very useful in various applications, they also have many limitations. DNA arrays can only detect sequences that the array is designed to detect. In other words, if the solution for hybridization with the array contains RNA or DNA species that do not have complementary sequences on the array, these species will not be detected. For gene expression analysis, this usually means that genes that have not been annotated in the genome will not appear on the array. In addition, non-coding RNA that has not been identified as expressed is usually not represented on the array. In addition, for highly variable genomes, such as those from bacteria, it is common to design arrays using information from the genome of a reference strain. Such arrays may lose most of the genes present in a given isolate of the same species.

Now, with the exception of genotyping, the cost of sequencing for all tests is more competitive than that of microarrays. When the cost is similar, sequencing has many advantages over microarrays. Sequencing is a direct measurement of which nucleic acids are present in the solution. Just count the number of sequences of a given type that exist to determine its abundance. The counting sequence has a linear relationship with the concentration, and the signal-to-noise ratio obtained by sequencing is only limited by the number of reads used for each sample.

Sequencing is a relatively unbiased method to measure which nucleic acids are present in the solution. Although sample preparation or different enzymes may be biased towards sequencing counting, unlike DNA microarrays, sequencing does not rely on prior knowledge of what nucleic acids may be present. Sequencing can also independently detect closely related gene sequences, new splicing forms, or RNA editing, which may be missed due to cross-hybridization on DNA microarrays. Due to these advantages and the reduction of sequencing costs, DNA microarrays are rapidly being replaced by sequencing. Almost all previous analyses performed on microarrays have been sequenced.