Our grateful thank to the charity Unique for their contribution to our on-air radio feature , which you can hear again via the audio player below, and our podcast report (episode 49 available from the 4th of August). Unique provide support, information and networking for anyone affected by rare chromosome and gene disorders. You can reach them via this link.
Genetic and Rare Disorders. A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene or multiple genes or by a chromosomal abnormality.
Rare Disorders. The European Union defines a disease or condition as rare if it affects fewer than 1 in 2,000 people within the general population. Currently, there are over 6,000 known rare diseases and new conditions are being described through medical literature on a regular basis.
What are genes and chromosomes? Genes are part of your body’s cells that store instructions for the way your body grows and works. Genes are passed from parents to children. Each person has more than 20,000 genes. Your genes make you the way you are — they help control things like your height, the curliness of your hair and the color of your eyes.
Sometimes the instructions that are stored in a gene change. This is called a gene change or a mutation. A gene can change on its own, or it can be passed from parents to children.
A gene change can sometimes cause health conditions, like cystic fibrosis and sickle cell disease. A gene change also can cause birth defects, like heart defects. Birth defects are structural changes present at birth that can affect almost any part of the body. They may affect how the body looks, works or both. Birth defects can cause problems in overall health, how the body develops or how the body works.
Any condition caused by a gene change is called a genetic condition (also called a genetic disorder). Some types of genetic conditions are caused by problems in one or more chromosomes. Chromosomes are the structures that hold genes. Each person has 23 pairs of chromosomes, or 46 in all. For each pair, you get one chromosome from your mother and one from your father.
Just like genes, sometimes chromosomes change. There may be too many or too few chromosomes, or part of a chromosome may be missing. These changes can cause chromosomal conditions (also called chromosomal disorders) in a baby. One of the most common chromosomal conditions is Down syndrome (when there are three copies of chromosome 21 instead of two). Parents can pass chromosome changes to their children, or they can happen on their own as cells develop.
Chromosomal disorders can result from changes in either the number or structure of the chromosomes. Changes in the number of chromosomes happen when there are more or fewer copies of a particular chromosome than usual. Changes in chromosome structure happen when the material in an individual chromosome is disrupted or rearranged in some way.
Changes in chromosome number. As previously highlighted, usually, every cell in a person’s body contains 46 chromosomes. Sometimes, however, a baby is born with either too many or too few chromosomes. The baby, therefore, has too few or too many genes or instructions. One of the most common examples of a genetic condition caused because of an extra chromosome is Down syndrome. People with this condition have 47 chromosomes in their cells instead of 46. This is because there are three copies of chromosome number 21 instead of the usual two.
Changes in chromosome structure happen when the material in an individual chromosome is broken and rearranged in some way. This may involve the addition or loss of chromosome material. This may happen in a number of ways which are discussed below. Changes in chromosome structure may be very subtle and hard to detect by scientists in the laboratory. Even when the change in structure is found, it is often hard to predict what effect the change will have on an individual child. This can be frustrating for parents who are keen to have as much information about their child’s future as possible.
Listen to this weeks radio report
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