|
Signs of Hearing Loss
Types of Hearing Loss
Causes of Hearing Loss
Genetics of Hearing Loss
Can My Child Hear?
|
Other Ways of Inheriting Hearing Loss
Read this page to find out about less common ways hearing loss can be inherited.
X-linked hearing loss
X-linked recessive inheritance causes hearing loss in only a small number (about 3%) of people with hearing loss.
- With X-linked recessive inheritance, only boys are affected.
- Girls can be carriers of the gene. That means they could pass it on to their sons in the future.
- If a mother is a carrier of the hearing loss gene, her sons will have a 50% chance of having hearing loss.
- If a mother is a carrier of the hearing loss gene, none of her daughters will have hearing loss. But half of them will be carriers.
- X-linked types of hearing loss can be a mix of conductive and sensorineural hearing loss.
X-linked means that the gene is on one of the sex chromosomes. Here’s how it works:
One of the pairs of chromosome is called the sex chromosomes. Males have an X and a Y chromosome (written XY). Females have two X chromosomes (written XX).
If there is a recessive gene for hearing loss on only one of the mother’s X chromosomes, she will have normal hearing. She would be called a “carrier.” Half of her children will get the hearing loss gene. Her daughters will get the normal gene on the X chromosome from their father. Sons won’t have a second X chromosome because they will have gotten the Y chromosome from their father. So they will have hearing loss even though they have only one copy.
In this picture the mother is a carrier of an X-linked hearing loss gene called Xd. Only her sons who get the Xd from her and the Y from their father will have hearing loss.
|
|
X-Linked Recessive Inheritance
|
Mitochondrial inheritance
Mitochondria (mi-toe-KON-dree-a) are parts of a cell that help produce energy. They have their own set of genes. Changes in mitochondrial genes can sometimes cause hearing loss.
- Mitochondria are passed from mother to child in the egg from the mother. Sperm from the father don’t pass mitochondria to the baby.
- Since mitochondria only come from the mother, only mothers can pass mitochondrial traits to their children.
- Mitochondrial deafness can be either syndromic or non-syndromic.
- One type of mitochondrial mutation (called A1555G) makes a person more likely to lose hearing after taking some antibiotics.
- Other types of mitochondrial mutations can cause hearing loss along with diabetes or neuromuscular (NUR-oh-mus-kew-lar) disease.
- Mitochondrial mutations are the cause of hearing loss only about 2% of the time.
|
