Patient's question:
Sure, I can help with that. However, you haven't provided any content to translate. Please provide the text you want to be translated into English.Doctor's answer:
Down syndrome, also known as trisomy 21, refers to a condition where the patient has an extra chromosome in the 21st pair (while the normal number is one pair). Down syndrome screening is calculated by measuring the levels of AFP and HCG in a pregnant woman's serum, combined with her age, weight, and gestational age to determine the risk value. The critical value is 1/275. A value greater than this indicates high risk, while a value lower than this indicates low risk. The probability of having Down syndrome (DS) in the general population (under 37 years old) is 1/750.