Chromosomes

There are chromosomes in every cell of your body. These chromosomes contain your DNA or genetic material, which determines how you look and how your body works. Chromosomes are made up of small pieces of DNA with a fixed place on the chromosome. Such a small piece of DNA is called a gene. Because each chromosome consists of a very long string of twisted DNA, there are many genes on a chromosome. Each gene has its own code that is used for creating a protein. Because your genetic information is stored in your genes, they control the build-up and development of your body.

Every human has 23 pairs of chromosomes, 46 in total. At conception, when an egg cell and a sperm cell merge, your mum gives you 22 autosomes (non-sex chromosomes) and one sex chromosome (an X chromosome) and your father gives you 22 autosomes and one sex chromosome (an X or a Y chromosome).

Your genetic material thus determines your physical and mental structure and development and so it can also play a role in the development of disorders, diseases and a different sexual development.

• You can inherit a hereditary disease or condition from your father or mother due to a fault in a certain gene, such an abnormality is called a mutation. The fault is, therefore, fixed in your genetic material and you can inherit the disease or condition but not necessarily so. The chance of inheritance differs per illness.
• You can also be the first in your family to develop a fault in the genetic material. For example, because you have a new mutation on a gene or a deviating number of chromosomes.

Sickle cell disease
Sickle cell disease is a hereditary blood disorder. It’s caused by a faulty piece of DNA that lies on one of your chromosomes.