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Hearing Loss & Genetics: Understanding the Basics Anna Frangulov, B.S. Research Coordinator Children’s Hospital Boston.

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Presentation on theme: "Hearing Loss & Genetics: Understanding the Basics Anna Frangulov, B.S. Research Coordinator Children’s Hospital Boston."— Presentation transcript:

1 Hearing Loss & Genetics: Understanding the Basics Anna Frangulov, B.S. Research Coordinator Children’s Hospital Boston

2 Why Hearing Loss is So Common?

3 Structure of the Ear

4 Sound wave Inside the Cochlea “snail” Hair Cells Nerve

5 Structure of the Ear Conductive HL Sensorineural HL

6 Genetic Infections Drug-Related Structural What Causes Hearing Loss? Unknown Traumas/ Exposures Non-Genetic

7 How Genetic HL occurs?

8 Chromosomes in Nucleus 23 Pairs of Chromosomes MOM DAD

9 One Chromosome Pair Genes “instruction manual”

10 Genes

11 Chromosome Pair Genes Mutation “error”

12 How Is Mutation Inherited?  Dominant ~15%  Recessive ~80%  X-Linked ~2%  Mitochondrial >2%

13 Dominant Inheritance Mutation “error"

14 Carrier Mutation “error"

15 How a Recessive Mutation is Passed? Carrier –No Hearing Loss Affected Child— Hearing Loss

16 Recessive Inheritance

17 If a parent has a dominant mutation, EACH of their children has a 50% chance of having hearing loss Dominant Inheritance Recessive Inheritance 90% of all children w/HL have normal hearing parents! Parent w/HL Parent w/o HL Child w/HL If two parents have a recessive mutation, EACH of their children has a 25% chance of having hearing loss

18 HOW? WHO? WHY?

19 HOW Do We Know If HL is Genetic?

20

21 WHO Should Have a Genetic Test?  Case A: Syphilis  Case B: CMV  Case C: Prematurity  Case D: High bilirubin level Everybody with Sensorineural HL Also 2 Mutations in Cx26!!

22 WHY Should We Have a Genetic Test?? Benefits for Genetic Testing  a definite cause  family members realize that they are carriers & determine risk factors for future children  helps to find appropriate treatment/ management

23 Limitations for Genetic Testing  does not necessarily find the answer  severity of HL may not be predicted  a person may have mutations, but not have HL

24 Things to Consider Things to Consider 1. Talk to knowledgeable professional  Primary Care/ Pediatrician  ENT  Audiologist Clinical Geneticist  Clinical Geneticist  Genetic Counselor  Clinical Molecular Geneticist

25 Things to Consider 2. What tests are done?  Cx26  Cx30  Mitochondrial Tests  Pendred 3. Cost

26 UNDERSTANDING TEST RESULTS (example Cx26)

27 What Does the Result Mean?  Two Mutations are Found  No Mutations are Found  Mutations w/Unknown Significance  One Mutation is Found ?? ~10% ~70% ~18% ~1%

28 One Mutation Found  Mutation unrelated to deafness  Test did not find 2 nd mutation  Dominant mutation  There may be a mutation in another gene

29 Future in Genetics and HL  More Genetic Tests GeneChip Technology

30 Research Studies  Connexin 26 Study- individuals with Cx26 mutations  Genetic Testing and Counseling Study - If you or your child has had genetic testing for hearing loss and you are willing to fill out a questionnaire  GeneChip Study - individuals with hearing loss who and parents with normal hearing  Novel Gene Discovery Study - five or more family members with hearing loss

31 Now also in Spanish! Educational Material

32 Helpful Information  Genetic Counselor - Rebecca Madore call to set an appointment or  Department of Clinical Genetics – To make appointment with Clinical Geneticist call  National Society of Genetic Counselors (NSGC)  Research Study Participation & Booklets Orders: Anna Frangulov or or


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