Genes are one of the basic units of life. Problems with genes can cause health or development problems. Some genetic disorders affect people from birth, others develop later in life.
Almost every cell in the body has a centre called a nucleus. In almost every nucleus, there are 46 chromosomes. Chromosomes are passed from parent to child, and are the vehicle for carrying all that a child inherits from their parents. Chromosomes are made of a chemical compound called DNA (deoxyribose nucleic acid). A gene is a small section of that DNA. There are more than 20,000 genes in the human body.
A genetic disorder is a health condition that comes about because of a problem with a gene or with a chromosome. A problem with a single gene is known as a gene mutation. You can have a gene mutation without it causing any problems. But some gene mutations can cause problems such as cystic fibrosis, Huntington's disease and haemophilia. If you have a problem with a chromosome, that will probably cause noticeable problems. Some people have a missing chromosome, some have an extra chromosome, some have a broken chromosome. Down syndrome, Turner syndrome and Klinefelter syndrome are all examples of chromosomal disorders.