Genes are very small structures inside almost every cell of the body.
Genes are instructions, or blueprints, that tell our bodies to grow and develop. They determine an individual's characteristics, such as height, eye and hair color, and blood type. There are about 100,000 genes, each of which has a specific instruction and function. They line up to form larger structures called chromosomes. Genetic disorders are caused when there is a change in the instructions coded by a particular gene and the gene can no longer perform its normal function.