The Process of DNA Testing

You have probably seen one of those shows where participants got the opportunity to undergo genetic testing to determine their ancestry. In Singapore, you can also have your DNA tested in accredited laboratories in the country whether it is for legal purposes like paternity tests or just for fun.

So, what happens during DNA testing and are the results reliable?

Types of Genetic Testing

Some of the genetic tests that you can have performed are the following:

  • Newborn Screening – This is done right after birth so that parents are given enough time to treat any genetic disorders early.
  • Carrier Testing – For families with history of genetic illnesses, it is sometimes required to have a carrier testing to identify individuals who carry the gene mutation. Couples who are planning to have a baby can also have this test done to ensure that the child does not suffer from any genetic defect if two copies of the gene mutation are present.

  • Prenatal Testing – Genetic changes in the fetus’s chromosomes or genes can be detected before birth especially if there is a risk. It can help couples decide whether they want to continue the pregnancy or terminate it in case giving birth is dangerous to the baby or the mother.
  • Preimplantation Testing – Couples who are worried about a genetic disorder in embryos created with assisted reproductive techniques will want to consider this.
  • Predictive and Presymptomatic Testing – This is like the newborn screening, but it also used to determine whether the child is at risk of conditions that will appear later in life.
  • Diagnostic Testing – Illnesses that are difficult to diagnose might require diagnostic testing to rule out those conditions. The result can be life-changing when choosing which treatment is best for the person.
  • Forensic Testing – The procedure is used for identification to implicate a crime suspect, identify a victim, or establish biological relationships between individuals.

Genetic Testing Procedure

DNA testing is divided into four steps such as extraction, quantitation, amplification, and capillary electrophoresis.

Extraction

The DNA, which is location in the nucleus of cells, are extracted by breaking open the nucleus to release the DNA into a solution.  The DNA molecules are also separated from other materials in the cell. Methods used to extract DNA can be manual or robotic in nature. Usually it will take 2 hours or more to extract the material through a robot system and 3 hours if it’s manual.

Quantitation

To ensure that the DNA is from the human and not from other sources, the quantity and quality must be determined. The amount of the DNA present can be crucial in the next step. The process takes between 1 hour to 2 hours to complete the quantitation using a sequence detection system.

Amplification

Copies of the material must be made through polymerase chain reaction. Why will it need copies? Sometimes the material is limited in quality and quantity, so making copies is essential. Then, heating and cooling of the samples take place through a thermal cycle. This can take two hours to complete.

Capillary Electrophoresis

The amplified DNA molecules must be separated to distinguish them from each other. This is done by applying an electric current to separate the large DNA molecules from the other sizes. This can take a maximum of 60 minutes to complete.

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