The most common reason a physician might recommend that a woman have maternal serum screening and a karyotype analysis is concern that her fetus may have Down syndrome. Go to the OMIM website at www.ncbi.nlm.nih.gov/omim and look up Down syndrome (OMIM 190685).

List the main symptoms of Down syndrome.

Key Concepts

Down Syndrome

Down syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of an extra copy of chromosome 21. This condition leads to a range of developmental and physical challenges, including characteristic facial features, cognitive impairment, and an increased risk of certain health issues. Understanding the genetic basis of Down syndrome is crucial for recognizing its symptoms and implications.

Maternal Serum Screening

Maternal serum screening is a blood test performed during pregnancy to assess the risk of certain genetic conditions, including Down syndrome. It measures specific substances in the mother's blood that may indicate an increased risk of chromosomal abnormalities in the fetus. This screening is typically done in the first or second trimester and helps inform further diagnostic testing if necessary.

Karyotype Analysis

Karyotype analysis is a laboratory procedure that examines the number and structure of chromosomes in an individual's cells. This test can identify chromosomal abnormalities, such as the extra chromosome associated with Down syndrome. Karyotyping is often used as a follow-up to screening tests to confirm or rule out genetic disorders, providing critical information for prenatal care.