Can changes in chromosomes cause disorders?
Yes; changes that affect entire chromosomes or large segments of chromosomes can cause problems with growth, development, and function of the body’s systems. These changes can affect many genes along the chromosome and alter the proteins made by those genes. Conditions caused by a change in the number or structure of chromosomes are known as chromosomal disorders. Many chromosomal disorders are not inherited. Human cells normally contain 23 pairs of chromosomes, for a total of 46 in each cell. A change in the number of chromosomes leads to a chromosomal disorder. A gain or loss of chromosomes from the normal 46 is called aneuploidy. Down syndrome is an example of a condition caused by aneuploidy–people with Down syndrome have an extra copy of chromosome 21, for a total of 47 chromosomes in each cell. Chromosomal disorders can also be caused by changes in chromosome structure. These changes are caused by the breakage and reunion of chromosome segments when an egg or sperm cell is forme
