Question

Because of its rapid turnaround time, fluorescent in situ hybridization (FISH) is commonly used in hospitals and laboratories as an aneuploid screen of cells retrieved from amniocentesis and chorionic villus sampling (CVS). Chromosomes 13, 18, 21, X, and Y are typically screened for aneuploidy in this way. Explain how FISH might be accomplished using amniotic or CVS samples and why the above chromosomes have been chosen for screening.

Accepted Answer

Step 1: Begin by explaining the concept of fluorescent in situ hybridization (FISH). FISH is a molecular cytogenetic technique that uses fluorescently labeled DNA probes to bind to specific chromosome regions. This allows visualization of specific genetic sequences under a fluorescence microscope. Step 2: Describe the process of sample preparation. Cells from amniotic fluid or chorionic villus sampling (CVS) are collected and cultured. The chromosomes within these cells are then fixed onto a slide to prepare them for hybridization with the fluorescent probes. Step 3: Explain the hybridization process. Fluorescently labeled DNA probes complementary to sequences on chromosomes 13, 18, 21, X, and Y are applied to the slide. These probes bind specifically to their target sequences on the chromosomes, allowing visualization of these regions. Step 4: Discuss the detection and analysis. After hybridization, the slide is examined under a fluorescence microscope. The presence, absence, or abnormal number of fluorescent signals indicates whether aneuploidy (abnormal chromosome number) is present for the screened chromosomes. Step 5: Explain the rationale for choosing chromosomes 13, 18, 21, X, and Y. These chromosomes are associated with common aneuploid conditions, such as trisomy 13 (Patau syndrome), trisomy 18 (Edwards syndrome), trisomy 21 (Down syndrome), and sex chromosome abnormalities (e.g., Turner syndrome and Klinefelter syndrome). Screening these chromosomes provides critical information about the most clinically relevant aneuploidies.

비슷한 문제에 대한 검증된 영상 답변:

주요 개념

Fluorescent In Situ Hybridization (FISH)

Aneuploidy

Amniocentesis and Chorionic Villus Sampling (CVS)