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Nonsyndromic Hearing Loss (DFNB1)
by Yael Rosenberg, RN
• Description
• Symptoms
• Incidence and Carriers
• Treatment
• Testing
• Resources and More
• Support Group
Description
Nonsyndromic Hearing Loss is a congenital, autosomal recessive genetic disorder that can be mild to profound, is non progressive and is due to damage of the nerves originating in the cochlea that supply the inner ear. There are no other abnormal clinical findings associated with this genetic mutation. Also referred to as Connexin 26.
Symptoms
Individuals with connexin-26 related deafness do not have any other medical issues and enjoy a normal life span. Infants and children affected by this disorder do not experience any problems with balance and start sitting and walking at the appropriate age.
Affected infants and young children do not experience balance problems and learn to sit and walk at age-appropriate times.
Incidence and Carriers
Disease frequency: 1 in 1,700 in Ashkenazi Jews, 1 in 7,000 for general population
Carrier frequency: 1 in 20 to 1 in 25 in Ashkenazi Jews, 1 in 35 in US Caucasian population.
The disease is transmitted through heredity. Both parents have to carry the mutated gene for there to be a possibility of transmission to their child.
If both are carriers:
• There is a One in Four chance that the child will inherit the mutated gene from each parent and have the disease
• There is a One in Four chance that the child will inherit normal genes from both parents and be completely free of the disease.
• There is a Two in Four chance the child will inherit one of a mutated gene from one parent and a normal gene from the other parent, and in this case, be a carrier like the parents, but free of the disease.
Treatment
Treatment for nonsyndromic deafness includes utilization of hearing aids as well as vibrotactile devices. For children over the age of 12 months with severe to profound hearing loss, cochlear implantation might be considered an option.
Testing
Diagnosis: made by physical, audiological and inner ear examinations, family history and molecular genetic testing is included.
Screening for Nonsyndromic Deafness carriers requires molecular genetic testing for DNA mutations.
Resources and More
American Speech-Language Hearing Associates
http://www.asha.org/hearing/disorders/causes.cfm
American Speech-Language-Hearing Association
10801 Rockville Pike
Rockville, MD 20852
Toll-free, voice or TTY: 800-638-8255
Available 8:30 a.m.-5:00 p.m. ET
email: actioncenter@asha.org
The Connexin-deafness homepage
The Deafness Research Group
http://www.crg.es/deafness/
Support Groups
Alexander Graham Bell Association
for the Deaf and Hard of Hearing
3417 Volta Place, NW
Washington, DC 20007
Tel: 202/337-5220
TTY: 202/337-5221
Fax: 202/337-8314
Email: info@agbell.org
Website: http://www.agbell.org
American Society for Deaf Children
3820 Hartzdale Drive
Camp Hill PA 17011
Phone: 800-942-2732 (parent hotline); 717-703-0073 (business V/TTY)
Fax: 717-909-5599
Email: asdc@deafchildren.org
http://www.deafchildren.org
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