What are the different types of chromosome studies?

Different types of chromosome studies include: karyotyping, fluorescent in situ hybridization, extended banding chromosome studies, and chromosomal microarray analysis. Chromosome studies are typically carried out from a blood sample, skin biopsy, or another tissue sample. 

1. Karyotyping is a test done to examine chromosomes in a sample of cells and identify specific genetic causes of diseases. Abnormalities in both the number and structure of chromosomes can pinpoint the cause of a genetic disorder. 
2. Extended banding is a test for examining chromosomes at a higher resolution than karyotyping. It differs from karyotyping in that smaller pieces of chromosomes are able to be studied. Thus, it is able to identify smaller structural chromosomal abnormalities that may not be visualized through a karyotype analysis. 
3. Fluorescent in situ hybridization is a test for determining how many copies of a specific DNA segment are present in a cell. It can also identify chromosomes with a structural problem. This test is used for detecting trisomy 21, and a baby with the disorder would have cells with three signals where the probe matched with three #21 chromosomes. 
4. Chromosomal microarray analysis can view chromosomes at an even higher resolution than FISH. This test looks for the identification of a change in DNA copy number. This alteration can also reflect changes in the population that do not cause genetic disorders. Types of chromosomal abnormalities include small chromosomal rearrangements, small duplicates of chromosomal material, or small deletion of chromosome material.