In the beginning, there were no such techniques for the diagnosis of disease in a fetus or embryo before it is born. Due to lack of this information whether a child carries any disease or not produced defective birth of a child such as chromosomal abnormalities, genetic disease and many other conditions. Parents do not want their child to be born imperfect. They want a healthy child without any disease. For this they have to go for prenatal testing so that they should know about any defect. One can also know about the gender of the unborn baby.

As the time passes, bioinformatics tools have opened the new ways for the detection of defective genes. Bioinformatics is a gigantic field providing with them great benefits. It provides solution to the problem. It has been used everywhere for solving many problems. Researchers who are trying to materialize this field so that one could find solutions.

As genes are units of heredity, they carry genetic information and hold the information to build or maintain an organism's cell. So genes plays significant role in one's life. If a single gene is defected a child will be born with various diseases. Single gene disorder is 1/100-1%. There may be some abnormalities about chromosome number; there are some that are related to biochemical assay. Family history also matters, as genetic disease are mostly related with the age of mother for example if maternal age is above 35 then there is a chance of abnormal child or if chromosomal abnormality is high in sisters and brothers then the chance of abnormality would be high for the child.

Prenatal testing is used for the detection of birth defects. It is applied in after 12th week of pregnancy. This test is useful when the genetic material has been completed. So that each gene can be detected if it carries any defect. Through prenatal testing an unborn will be safe from any deformity in future.

There are many techniques for diagnosis of genetic diseases. For the prenatal testing sample is taken from foetus through a needle. Diagnosis technique called amniocentesis in which needle is injected in amino sac and the sample is taken then this sample is cultured and single is taken and different techniques will be performed. This method is very accurate either performs DNA test or microscopy.

Some other techniques for the diagnosis of genetic diseases are:

1. Chronic villus sampling (placental tissue)
2. Percutaneous umbilical chord (blood sampling)
3. Fetoscopy ( fetal tissue biopsy)
4. Ultrasound (check different structural abnormalities)
5. Pre-implantation diagnosis
6. Fetal cell sorting in maternal blood.

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