Hereditary deafness is hearing loss that is inherited or passed down from parents to their children. This type of hearing loss may be inherited from one or both parents who may or may not have a loss of hearing themselves. Hereditary material or genes are located on chromosomes which are found in each cell of the body. Genes provide instructions for specific traits or characteristics such as hair color or blood type.
Defective genes can also pass along traits such as hearing loss or speech and language disorders.
The hereditary hearing loss that results from defective genes may be syndromic or nonsyndromic, dominant or recessive. Syndromic hearing loss is associated with specific traits additional to hearing impairment. For example, hearing, balance and visual problems occur in Usher syndrome. Nonsyndromic hearing impairment has hearing loss as its only characteristic. Dominant transmission of deafness requires only one faulty gene, from either the mother or father to cause the hearing loss, whereas recessive transmission of deafness requires a faulty gene from both the mother and father.