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Overview of the Respiratory System

Author(s): Nancy Moreno, PhD, Deanne Erdmann, MS, and Sonia Rahmati Clayton, PhD
Showing Results for: human Return to Presentation

Karyotyping

The image in the slide shows the karyotype from a normal human male (note one X and one Y chromosome). Karyotyping is a laboratory technique which allows microscopic visualization of the number and gross structure of the chromosomes within a cell. This karyotype would be abbreviated 46,XY: 46 for the number of chromosomes and XY for the sex chromosome makeup. If this karyotype were from a normal female, there would be two X chromosomes and no Y chromosome. A normal female would be designated 46,XX.

The signs and symptoms of genetic disorders caused by disruptions in the structure or number of chromosomes in the human genome are extremely variable and typically related to the particular chromosomal abnormality involved. In the case of structural rearrangements of chromosomes, most effects are likely due to disrupted expression or regulation of genes at or near the sites of structural rearrangements. In the case of chromosomal aneuploidies (the condition of having more or less than the normal number of chromosomes), alteration of the normal copy number of genes on the involved chromosome are likely the cause of most abnormalities.