CHOC Children's
MEDICAL GENETICS

The Difference Between a Chromosome Abnormality and a Single Gene Defect

What is the difference between a chromosome abnormality and a single gene defect?

There are approximately 25,000 genes contained on the 46 chromosomes in each cell of our body. This means that one chromosome contains thousands of genes. A person can have normal chromosomes in number and structure, but still have a disease or condition caused by a mutation in one or more of the genes on the chromosomes. A single gene defect usually does not cause the chromosome structure or number to be abnormal.

Similarly, a person can have normal genes, but, because they have extra copies of genes due to a chromosome abnormality, the extra copies can cause the genes to not work properly.

This is an important distinction to make. Consult your physician or genetic counselor for more information.

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Online Resources of Medical Genetics

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It is important to remember the health information found on this website is for reference only not intended to replace the advice and guidance of your healthcare provider. Always seek the advice of your physician with any questions you may have regarding a medical condition. If you think you may have a medical emergency, call your physician or 911 immediately.

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