Hearing loss, genes, DNA and mutations

Genes are chemical units found inside all cells of the human body. Inside the cell the genes form specific structures called chromosomes, which make up our DNA and hold our hereditary characteristics. Every cell in the human body is composed of some 30,000 genes.

Some of the genes in ear cells affect our hearing and help determine how sounds are turned into signals that the brain understands.

At times, changes occur in the DNA of the genes, affecting their functioning. If these mutations occur in a gene with important information about our sense of hearing, the result may be hearing loss or, in extreme cases, deafness.

Inherited from parents

All human genes exist in two copies passed on from the mother and the father, respectively. The risk of hearing loss may depend on whether a possible mutation is dominant or recessive. A dominant mutation causes hearing loss if just one of the inherited copies from the parents is damaged. Recessive mutations manifest themselves as hearing loss only if both copies are damaged, i.e. if both parents are carriers of the gene mutation.

Different types of hearing loss

Pinpointing the genetic causes for a specific hearing loss is complicated. Many different genes can cause the same type of hearing loss and the same genes can also be involved in different types of hearing loss. Two people with the same gene mutation may still have very different levels of hearing ability.

In the next 10 to 20 years a wide range of new hearing loss treatments may be introduced based on our increased knowledge of our genes.

Source: "Science, Medicine and the Future. New Interventions in Hearing Impairment." British Medical Journal, & "Hearing Genes", One In Seven

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