Genetics is the study of genes and genetic variation.It is to understand the what causes the disease in the family.
All of us know that our body is made up of cells. Each cell contains a nucleus. Nucleus has the genetic makeup of the individual in the form of chromosomes. All of us have 23 pairs of chromosomes. These chromosomes have tightly coiled DNA and on this DNA a number of genes reside. If the nucleus is a book, then the chromosome is a chapter in the book and gene is a particular line in that chapter.
It is important to understand the genetic problem in the family because it has multiple health implications for your family as a whole. When multiple family members have similar problem then the genetic disease is suspected. Moreover, when there are early deaths in childhood or in adulthood without any known cause suspect genetic disease. Developmental delay, autism, congenital heart disease, multiple miscarriages and pregnancy ultrasound showing any abnormality may also suggest some genetic cause.
Genetic test is a broad term. It encompasses broad range of testing to identify a disorder ranging from Sanger sequencing, next generation sequencing, multiplex ligation probe amplification, karyotype to microarray and so on. There is no such broad test. The type of test will depend on what disorder is suspected in you or your family member.
Prenatal screening is the investigation which is conducted in the pregnant women to determine the chance of baby having a specific chromosomal disorder. It is a screening test which means that it just tells you that you are at increased risk and warrants further testing. They are usually carried out in the first trimester or second trimester.
It is a type of non invasive screening test to detect Down syndrome babies. In this a simple blood sample is taken to determine the risk. It is a high efficiency screening test and is not a diagnostic test.There are various methods available for testing and needs to be determined by taking a proper history and examining all the documents of pregnancy.