Ledesma Audiological Center Inc. — Hereditary Hearing Loss
Genes are the building blocks of the body which is composed of DNA. Every child inherits half of the genes from each parent. Because of that, there is a possibility that he or she have inherited genes that were defective, causing health issues, such as hearing loss or impairment.
Hearing loss or deafness is one of the more common congenital defects. It affects more than 3 out of 1,000 babies, according to American Academy of Otolaryngology– Head and Neck Surgery. One of the factors of hearing impairment that scientist are still studying is the inherited defective genes, since 60% of deafness occurring in infants are considered as hereditary hearing loss, which may not be all present at birth but can develop later in life. Also, other factors that may cause hearing loss are medical problems, trauma and environmental exposure.
There are two distinctions between hearing impairment — Nonsyndromic and Syndromic. There is, actually, a larger percentage of nonsyndromic, which is 70%, than syndromic, which is only about 30%.
Nonsyndromic hearing impairment can be either partial or total hearing loss. However, it is not associated with other symptoms or sign related to other disorders. It can be unilateral, meaning in one ear, or bilateral, meaning in both ears.
On the other hand, syndromic hearing impairment is related with other clinical abnormalities that affects the other parts of the body. It can also be expressed in a scale of mild to severe depending on the combination of associated symptoms.
Over the last decade, researchers have identified several genes that are accountable for hereditary deafness or hearing impairment. One of the common gene mutations that lead to hearing loss is GJB2, which is considered as a recessive genetic disorder meaning both genes were defective. Studies showed that 50% of person with recessive nonsyndromic hearing loss, GJB2 mutation can be found. To help individual who are at risk of possibility on having a child with hearing impairment, screening test for GJB2 gene are available.
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