What is the difference between Down syndrome screening and DNA testing?

Down syndrome screening is a clinical screening of the chromosomes of pregnant women and fetuses. It can also be performed after the child is born to ensure that there is no risk of any genetic disease and some potential genetic factors. DNA testing is to test the patient's family members for blood type, height, personality, etc. These are two completely different testing methods.

DNA testing

Gene is a functional fragment on the DNA molecule, the basic unit of genetic information, and the most basic factor that determines all biological species. Gene determines a person's birth, aging, illness and death, is the cause of health, beauty and longevity, and is the manipulator and regulator of life. Therefore, wherever there is life, there are genes. The existence and decline of all life are determined by genes. Your appearance, height, weight, skin color, personality, etc. are all inseparable from genes.

Genetic testing is a technique that involves testing DNA in blood, other body fluids, or cells.

Understanding Genes

Gene (Mendelian factor) refers to a DNA or RNA sequence that carries genetic information (i.e. a gene is a DNA or RNA fragment with genetic effects), also known as a genetic factor, and is the basic genetic unit that controls traits. Genes express the genetic information they carry by directing the synthesis of proteins, thereby controlling the characteristics of individual organisms.

Down syndrome screening

Basic Overview

Down syndrome is also called trisomy 21.

The most common chromosomal aneuploidy disease is one more pair of 21 chromosomes than a normal person. Down syndrome screening is performed at a specific gestational week by testing the levels of PAPPA, AFP, HCG, uE3 and Inhibin A in the pregnant woman's serum, combined with clinical information such as the pregnant woman's age, gestational age, weight, whether she smokes and has insulin-dependent diabetes, and calculating the risk value through risk assessment software.

The critical value is 1/250-380 and may vary due to different methodologies. Greater than is high risk and less than is low risk. The probability of having Down syndrome DS in the general population under 35 years old is 1/750. According to the examination time, it is divided into early pregnancy 9-13 weeks and mid-pregnancy 14-21 weeks.