Genetic genealogy is a term used for when someone combines information about genetics with genealogy research about a particular family. This involves using DNA in order to determine how closely related two individuals are. It can also be used to find out if certain genetically hereditary diseases, conditions, or disorders, are present in your family tree.
In general, if you are considering having a genealogy company take a close look at your DNA, it is for one of two reasons. It can be used to confirm if you are, in fact, genetically related to another person. In some cases, genetic genealogy can be used to find out where in the world your family line originated from. Or, if you have reason to suspect that your family might carry the genes for certain genetic diseases, you might want to have that suspicion scientifically confirmed or denied. This is often used when a person is considering having children, in order to figure out the probability of the children inheriting a particular genetic disease.
Tay-Sachs Disease is something that occurs when there is a defect in the gene on chromosome 15 that codes for the production of an enzyme called Hex-A. The disease causes progressive destruction of the nervous system. If one parent carries the gene for Tay-Sachs, their child has a 50% of carrying the gene. If both parents are carriers, each child has a 25% chance of having Tay-Sachs disease, a 50% chance of carrying the gene, and a 25% of not carrying the gene and not having the disease. This disease can happen in any population, but is most common in Eastern European (Ashkenzai) Jews.
Hemophilia is caused by a gene mutation on the X chromosome. This is a bleeding disorder that causes a person’s blood to clot much more slowly than what would usually be expected. A female who carries this disorder has a 50% chance of passing it to her male children. This is because the disease is recessive. A female has two X chromosomes. In order for a female to have hemophilia, both of her X chromosomes have to have that mutation. If she only has one X chromosome affected, she will not have hemophilia. Males only have one X chromosome. If they inherit an affected gene, they will have hemophilia. Both males and females can have hemophilia, but it is much more common in males.
Down Syndrome is a condition that is related to chromosome 21. People who have Down Syndrome may have learning difficulties, and often have a characteristic facial appearance. This person has an increased risk of heart defects, digestive problems, and low activity of the thyroid gland. This condition is inherited when an error in cell division causes an extra chromosome to develop.
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