Find a healthcare providerThe role of genetics
The underlying cause of rare genetic diseases of obesity can be found in genes that aren’t working properly. And though the biology that explains it can get complicated, you will probably find it helpful to have a basic understanding of genetics when you speak to your doctor.
Genes
Genes are your body’s instruction manual. They determine how your body grows, develops, and functions.
Genes are passed down to you from your parents. While genes can determine obvious traits like eye color and hair color, they are also responsible for genetic conditions like rare genetic diseases of obesity.
We have two copies of most of our genes—one from our mother and one from our father. All of us have changes in our genes, called variants, which make us unique. Not all genetic variants cause diseases, but some can.
Sometimes you need two copies of a certain gene variant—one from your mother and one from your father—to result in disease. Other times, just one will cause disease.
Occasionally, a gene variant for a rare condition will be present in both the mother and the father. When they have a child, that child may inherit two copies of the disease-causing (pathogenic) variant. If the child develops symptoms of the condition, the condition is called an autosomal recessive (AR) condition. Many rare genetic disorders of obesity are passed down from the parents to their child in this AR pattern.
You can carry a gene but not be affected
If you have only one copy of the gene with a disease-causing variant, you are considered a carrier but will generally not have any symptoms of the disease.
If both parents carry the gene variant for a disorder, each child they conceive will have:
Genetic predisposition vs genetic variants
While rare genetic diseases of obesity are caused by disease-causing gene variants, there are other forms of obesity that appear to run in families but do not follow a predictable pattern or have the same early and severe symptoms.
Two ways that you can inherit obesity from your parents are:
- A genetic predisposition to obesity, or
- A genetic variant that causes obesity
Having a genetic predisposition to obesity means that you are more likely to develop obesity than people with a different genetic makeup. Although obesity may run in your family, it doesn’t mean you will develop obesity. Other factors like diet, activity level, and even where you live can influence whether or not you develop obesity.
Inheriting a genetic variant that causes a rare genetic disease of obesity is different from a genetic predisposition. If you inherit a specific gene variant, you are likely to develop obesity, even if you change your lifestyle or environment.
