Limb-girdle muscular dystrophy

Inheritance

How is limb-girdle muscular dystrophy inherited?

Limb-girdle muscular dystrophy type 1 (LGMD1)

Limb-girdle muscular dystrophy type 1 (LGMD1) is inherited in an autosomal dominant manner. We all inherit two copies of each of our genes from our parents. One copy comes from mom and one comes from dad. An autosomal dominant condition means that one altered copy of the associated gene is enough to cause the symptoms of the condition. People with LGMD type 1 have one normal copy of the associated gene and one altered copy. An alteration in a gene can also be called a mutation. If a parent has LGMD1, each of their children has a 50% chance of inheriting it.

Limb-girdle muscular dystrophy type 2 (LGMD2)

Limb-girdle muscular dystrophy type 2 (LGMD2) is inherited in an autosomal recessive manner. We all inherit two copies of each of our genes from our parents. One copy comes from mom and one comes from dad. An autosomal recessive condition means that a person must have a mutation in both copies of the associated gene in order to show symptoms of the condition.

The parents of an individual with LGMD2 are said to be carriers of the condition. This means that they have one copy of the genetic change associated with the condition. They will not have symptoms of the condition. Each sibling of a person with LGMD2 will have a 25% chance of also inheriting the condition, providing that they have the same two parents. Individuals who are affected with LGMD2 are unlikely to have children who are affected with the condition. This would only be possible if their spouse happened to also be a carrier of the same subtype of LGMD2. While this situation is rare by chance alone, if you are a blood relative of your spouse (for example a cousin or second cousin) the odds that you may both carry changes (mutations) in the same gene is much higher.

It is important to know that we cannot control which genes a child inherits. We also cannot control the occurrence of new changes (mutations) that occur in our egg cells, sperm cells, or in the early cells of a baby. These changes occur at random. LGMD types 1 and 2 are not caused by the action or inaction of anyone.

If you are concerned about the risk of having a child with LGMD and the options available, you may wish to speak to a certified genetic counselor, who can answer your questions and tailor the information to your specific situation. A list of genetic counselors is available on the National Society of Genetic Counselors website as well as on the Canadian Association of Genetic Counsellors website.

SOURCE: Emory University - Department of Human Genetics in collaboration with ThinkGenetic • https://www.thinkgenetic.com/diseases/limb-girdle-muscular-dystrophy/inheritance/18259 • DATE UPDATED: 2016-06-16

References

http://ghr.nlm.nih.gov/gene/SGCA

https://www.counsyl.com/services/family-prep-screen/diseases/limb-girdle-muscular-dystrophy-type-2d/

http://ghr.nlm.nih.gov/gene/SGCB

https://www.counsyl.com/services/family-prep-screen/diseases/limb-girdle-muscular-dystrophy-type-2E/

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