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Gene mutations

Sometimes operations at the cell level can go wrong, resulting in changes to the normal chemical patterns in DNA. This change to DNA is called a mutation, and it can affect the way the genes containing that DNA operate. Mutations are not necessarily bad--every human has an estimated eight to ten genes that are mutated, and most of these have little or no impact on the body.

However, if a gene that controls a vital cell function--like the production of enzymes required for waste breakdown--is mutated, problems can occur, including certain diseases. This is the case with lysosomal storage disorders (LSDs): people with these diseases have mutated forms of the genes responsible for producing enzymes that break down certain fatty waste products. The mutated gene doesn’t operate properly, so the enzymes aren’t produced in sufficient amounts. Thus the waste products don’t get broken down and instead are stored in cells’ lysosomes, causing a variety of symptoms.

Inheritance of gene mutations and genetic diseases

If a gene mutation arises within a single cell in the body, it will likely have little effect because the majority of the body’s cells will still have the normal gene. Even as cells continue to replicate themselves, most of the replications will come from normal cells, so the number of cells with the mutation will remain negligible.

However, if a mutation occurs in a sperm or egg cell, the mutated gene will get passed onto offspring during sexual reproduction. Since the offspring’s very first cell carries the mutated gene, every subsequent cell replicated from it will also have the mutation. Whether the affected gene causes a genetic disease depends on whether it is dominant or recessive as well as on the condition of the other gene in its pair.

Inheriting Gaucher disease

Gaucher disease is caused by a mutated gene that does not produce sufficient quantities of the enzyme glucocerebrosidase. This gene is recessive, meaning that its faulty operation will be “overridden” by the presence of an unaffected gene in the other half of the pair. Thus if a person inherits the Gaucher gene from only one parent, the other unaffected gene will still allow enough enzyme to be produced for the person to remain healthy. If a person inherits the Gaucher gene from both parents, however, they will develop Gaucher disease. A person who inherits the Gaucher gene from only one parent is called a carrier and can still pass on the mutated gene to his or her own children.

To learn more about the inheritance of Gaucher disease, visit the Genetics and Gaucher page.

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