Karyotyping

Chromosome analysis or karyotype is a test that evaluates the number and structure of someone’s chromosomes to detect abnormalities. Chromosomes are thread-like structures in the nucleus of every cell and contain the genetic blueprint of the human body. Each chromosome contains thousands of genes in specific locations. These genes are responsible for a person’s inherited physical characteristics and have a major impact on growth, development, and body function.

Humans have 46 chromosomes or 23 pairs. 22 pairs are found in both sexes (autosomes) and one pair (sex chromosomes) is present as XY (in males) or XX (in females). Normally, all cells in the body that have a nucleus will contain one complete set of 46 identical chromosomes, except for reproductive cells (eggs and sperm), which contain half a set of 23 chromosomes. This half set is the genetic contribution that will be inherited by a child. During fertilization, half sets from each parent combine to form a new set of 46 chromosomes in the developing fetus.

Chromosome abnormalities include changes in number and structure. For numerical changes, anything other than one complete set of 46 chromosomes is considered to have a change in the amount of genetic material present and can cause health and developmental problems. For structural changes, the significance of the problem and the severity of it depends on the chromosome affected. The type and degree of problems can vary from person to person, even when there is the same chromosome abnormality.