Wikia

Clinical: Approaches · Group therapy · Techniques · Types of problem · Areas of specialism · Taxonomies · Therapeutic issues · Modes of delivery · Model translation project · Personal experiences ·

AR Sensorineural Hearing Loss (DFNB1/Connexin 26)

IntroductionEdit

Acknowledge prior phone contact
What information have you been given already?
Have you done any research on your own? What have you found out?
What concerns or questions would you like to have answered today?
Outline session

Complete Medical HistoryEdit

Complete Family History and PedigreeEdit

PrevalenceEdit

DFNB1 accounts for 50% of AR sensorineural hearing loss
Prevalence is ~14/100,000
- 1/2000 congenital hearing impairment
- 70% of these are nonsyndromic
- 80% of nonsyndromic hearing loss is AR
- 50% of these are due to GJB2 mutation
1/30 people in general population are carriers

GeneticsEdit

Gene: GJB2
Chromosome location: 13q11-12
Protein: Connexin 26
- Gap junction protein
- Involved in conducing signal to the brain
Autosomal recessive inheritance
- 25% risk of hearing loss for future children
- 50% risk of being a carrier for the mutation
- 25% risk of being an unaffected noncarrier

Molecular TestingEdit

Detects 95% of disease-causing mutations
~66% of mutations - 35delG
~30% of mutations - other GJB2 mutations
~4% mutations - unknown
carrier testing is available and can be offered to at-risk family members
prenatal testing is available but rarely pursued

Clinical FeaturesEdit

nonprogressive sensorineural hearing impairment
- severe to severe-profound hearing loss
- diagnosed by Auditory Brainstem Response or pure tone audiometry and presence of no related anomalies
no other associated health problems
no balance problems

ManagementEdit

When diagnosis is known or suspected
- Assessment of auditory acuity by ABR or pure tone audiometry
- Fitting with hearing aids
- Early intervention
Follow-up care
- semiannual examination by physician familiar with hereditary hearing impairment
- repeat pure tone audiometry to confirm stability of loss
- consideration for cochlear implants
prelingual deafness associate with decreased cognitive skills and decreased math skills
- early intervention can help ameliorate these affects

Psychosocial IssuesEdit

Deaf child born to hearing parents
How did you feel when you first found out?
How have your feelings changed?
How have other family members reacted?
Have you been in contact with any other families?
Have you been in contact with any support groups?

ResourcesEdit

American Society for Deaf Children

PO Box 3355

Gettysburg, PA 17325

Phone: 717-334-7922

Fax: 717-334-8808

Email: ASDC1@aol.com

[1]

National Association of the Deaf

814 Thayer

Silver Spring, MD 20910

Phone: 301-587-1788

Fax: 305-587-1791

Email: NADinfo@nad.org

[2]

ReferencesEdit

Geneclinics: Nonsyndromic Hearing Loss and Deafness, DFNB1
National Information Center on Deafness
Clinical Genetics Lecture

NotesEdit

The information in this outline was last updated in 2002.

Material obtained under GFDL Licence from http://en.wikibooks.org/wiki/Handbook_of_Genetic_Counseling

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License."