More than 24,000 children are born with hearing loss in the United States each year. Boys Town National Research Hospital is a national leader in the diagnosis and treatment of children with moderate to profound hearing loss.

Information on Hearing Loss - Genetics and Deafness - Autosomal Recessive Inheritance

Genes are the basic unit of inheritance. They provide the instructions for growth and development of the single cell of a fertilized ovum into the complex structure of a baby. Many continue to provide instructions for the production of proteins needed for bodily functions throughout a person's lifetime. We have two copies of our genes with one copy coming from our mothers and the other coming from our fathers. The two copies in a pair of genes may not have identical instructions. When the two instructions are different, the dominant one is the one that gets expressed and the other one is called recessive. Recessive genes are expressed only when both copies in the pair have the same recessive instruction. An autosomal recessive gene is one that is carried on one of the 22 pairs of chromosomes which are not sex chromosomes.

A person with an autosomal recessive hearing loss (HL) would have to have two recessive genes for HL in that particular pair of genes. A person with a normal gene and a HL gene would not have a HL, but would be considered a carrier. Generally the HL gene has been passed down through the carrier's family for generations. A carrier has no way of knowing that he or she has a HL gene until having a child with HL. Then it becomes apparent that the individual and the individual's spouse each is a carrier. All of us have several recessive genes, each of which could cause significant problems for our children if it happened to get paired up with the same recessive gene from our partner.

The mother and father in the diagram are carriers of a gene for HL designated with an r. They also have one normal gene designated with an R. When they have a child each will pass on one of those genes. If they both pass on the R, the child will have two normal messages, not have HL and cannot pass the HL gene to his children. There is 1 chance out of 4 or a 25% chance for the child of two carriers to receive both normal genes. If one parent passes on the R and the other the r, the child will have one normal message, not have HL, and be a carrier like the parents. There are 2 chances out of four, or a 50% chance of the child of two carriers being a carrier also. If both parents pass on an r, the child will have no normal message and will have HL. There is 1 chance out of 4 or a 25% chance that the child of two carrier parents will receive both HL genes and have HL. The chance of carrier parents having a child with HL is the same with each pregnancy. If they have one child with HL, it does not mean that their next child will not have a HL also. The genes are passed on in a random manner and what has already happened in existing offspring has no influence on future offspring.

Date Originally Created: Summer of 1988

The information presented here first appeared in publications of the Boys Town National Research Register for Hereditary Hearing Loss, the National Institute on Deafness and Other Communication Disorders (NIDCD), Hereditary Hearing Impairment Resource Registry (HHIRR), or the Boys Town Research Registry for Hereditary Hearing Loss.

The Boys Town Research Registry for Hereditary Hearing Loss

The Boys Town Research Registry for Hereditary Hearing Loss (Registry) is designed to foster a partnership between families, clinicians and researchers in the area of hereditary hearing loss/deafness through three primary functions. First, the Registry disseminates information to professionals and families about clinical and research issues related to hereditary deafness/hearing loss. Second, the Registry collects information from individuals interested in supporting and participating in research projects. This information is used to support the third function of the Registry - matching families with collaborating research projects.

For more information, contact us at:

Research Registry for Hereditary Hearing Loss
555 N. 30th Street Omaha, NE 68131
800 320-1171 (V/TDD)
402 498-6331 (FAX)