Send us your comments. Genetic disorders are caused by mutations in a gene or a set of genes. Mutations are changes in the DNA sequence of a gene. They can happen at any time, from when we are a single cell to when we are 90.
Some people say that there are disorder genes.
It is not a gene, or genes, however, that cause the illness, but a mutation that causes the normal genes to operate improperly. It is better to say that there are mutated genes that cause genetic disorders. Some mutations do cause disorders, but others do not. In some disorders entire chromosomes , or large segments of them, are missing, duplicated, or otherwise altered. Down Syndrome and Turner's Syndrome are examples of this type of disorder.