The road map for the building of the proteins in the body is the genes. It is worth mentioning that the proteins are the basic units of all the body’s organs, including the eyes, the ears, the heart, the hair, the lungs…etc. Every one of us inherits half of his or her genes from one parent and the other half from the second parent. If the genes inherited from one or both parents are defective, then the congenital anomalies will show.

Deafness or hearing loss is a very common congenital disease; nearly three out of every thousand babies are born with this birth defect. Actually, the inherited genes are responsible for about sixty percent of the hearing loss in babies. Furthermore, some recent studies are suggesting that the partial and the complete loss of hearing ability in the senior people are also due to the genetic factors.

The hereditary hearing loss can be classified into the following two main categories: non-syndromic and syndromic. The non syndromic deafness accounts for approximately seventy percent of all cases of the hereditary hearing loss. Non-syndromic hearing loss is the type of inherited deafness which isn’t accompanied with other symptoms, while syndromic hearing loss is associated with some anomalies in different parts of the body. Various types of the non-syndromic hearing loss are usually termed according to their mode of inheritance. Mostly, non-syndromic hearing loss is due to the damage of one of the parts of the inner ear. The inner ear is normally formed of three main structures; the cochlea that aids in the processing of the sounds, the nerves to transmit the received information to the brain, and finally the structures responsible for the balance. Sensorineural hearing loss is the type of the deafness, which is
caused by the inherited alterations in the structures of the inner ear.

The conductive deafness is the loss of hearing due to the changes in the structures of the middle ear. The middle ear consists of three small bones, which transmit the sounds from the eardrum to the inner ear. Some types of the non-syndromic hearing loss, especially a form known as DFN3, are caused due to some changes in both; the middle ear and the inner ear, and this type is known as mixed deafness.

The Inherited hearing impairment can be unilateral (affects one ear) or bilateral (affects both ears). Besides, the severity of the hearing loss can vary from the difficulty to understand low speech (mild type) to the failure of hearing the very high sounds (profound type).