If you’re wondering whether or not hearing loss is genetic, it can be, but it isn’t the most likely cause of hearing loss. Of the more than 20 different causes of hearing loss listed by the World Health Organization, noise-related and age-related hearing loss remain the two biggest causes.
When Is Genetic Hearing Loss Most Present?
Although genetics plays a role in hearing loss in adults, it plays a much larger role in hearing loss in children.
Studies have shown that eighty percent of prelingual hearing loss cases (prelingual meaning hearing loss that occurs before a child is capable of understanding or using spoken language) are attributable to genetic causes.
Are There Different Kinds of Genetic Hearing Loss?
Non-Syndromic Hearing Loss
This kind of hearing loss is not associated with any other identifiable medical conditions or syndromes. This type of hearing loss has been linked to over 70 different genetic loci in its pathogenesis.
Quote [A genetic loci is the specific, fixed position of a gene or genetic marker on a chromosome.]
These fall into additional categories based on whether a gene is dominant or recessive, X-linked or involves a mitochondrial fashion, with autosomal recessive SNHL, presenting in 75 to 80% of cases.
How Does A Genetic Difference Impact Hearing?
To illustrate how complex a hearing loss involving genetic components can be, a specific subset of Autosomal recessive SNHL called Connexin 26 accounts for 30 to 40% of all cases. This condition occurs when Connexin 26, a protein crucial for hearing, undergoes mutations.
Because this protein helps form gap junctions, which are specialized channels that allow for the exchange of ions and molecules between cells, it has an outsized impact on cells that require specific ions or molecules to function.
Hair cells use potassium ions in a substance called endolymph. Endolymph is a liquid high in potassium ions and low in sodium ions. Its electrochemical makeup helps it convert energy from your hair cells’ movement into nerve signals that your brain can interpret.
If the hair cells in your inner ear that detect sound vibrations can’t replenish their potassium supply, they don’t have the ions they need to transmit sound via sensory transduction to the brain.
That genetic difference doesn’t prevent sound from being detected, but it interrupts the body’s ability to process it into a signal that the brain can interpret.
Syndromic Hearing Loss
The second major type of genetic hearing loss is associated with other clinical deficiencies and organ systems. This category includes over 400 different syndromes.
The severity of hearing loss can range from mild to profound, and conditions also cover the same recessive, dominant and X-linked categories of loci that non-syndromic hearing loss does.
Should You Have Your Child Tested?
The sooner a child receives a diagnosis, the better. Because genetic hearing loss is most commonly identified in children, Bangor Audiology always recommends that parents make sure their child undergoes a newborn hearing screening.