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Early Hearing Detection and Intervention - Promoting Communication from Birth

This article discusses the causes of prelingual hearing loss, including genetic and environmental factors. It also explores the various genetic research designs and identifies specific genes associated with nonsyndromic hearing loss. Additionally, it highlights the risk factors for hearing loss and the importance of early detection and intervention.

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Early Hearing Detection and Intervention - Promoting Communication from Birth

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  1. Early Hearing Detection and Intervention …Promoting communication from birth

  2. Sensorineural Function of the Cochlea “With over a million essential moving parts, the auditory receptor organ, or cochlea, is the most complex mechanical apparatus in the human body.” (Hudspeth 1985)

  3. Causes of Prelingual Hearing Loss 50% Genetic 50% Environmental 24% CMV intrauterine infection Other infections Rubella Bacterial Meningitis Toxoplasmosis NICU-related hypoxia Rh incompatibility ototoxic medications low birth weight 30% Syndromic (>400) 70% nonsyndromic (usually sensorineural) 22% autosomal dominant (29 loci) 77% autosomal recessive (30 loci) 1% X-linked (8 loci) <1% mitochondrial (2 loci)

  4. Causes of Prelingual Hearing Loss Recent Genetic Research Designs: Include people diagnosed with hearing loss in childhood Exclude children with syndromes Exclude children with known risk factors

  5. Prelingual Hearing Loss 50% Genetic 50% Environmental 24% CMV intrauterine infection Other infections Rubella Bacterial Meningitis Toxoplasmosis NICU-related hypoxia Rh incompatibility ototoxic medications low birth weight 30% Syndromic (>400) 70% nonsyndromic (usually sensorineural) 22% autosomal dominant (29 loci) 77% autosomal recessive (30 loci) 1% X-linked (8 loci) <1% mitochondrial (2 loci)

  6. Nonsyndromic Hearing Loss Unknown: DFNA5 K+ channel: KCNQ4 Connexins: GJB2 (Connexin 26) GJB3 GJB6 Cytoskeleton: MYO7A MYO15 DIAPH1 OTOF Extracellular Matrix: TECTA COCH Transcription Factors: POU3F4 POU4F3 Mitochondrial: 12S rRNA tRNASer

  7. Nonsyndromic Hearing Loss Single genes (connexin 26) Gene + environment (mitochondrial + ototoxic medications) Gene + gene (mitochondrial plus other) Other gene-environment interactions?

  8. Causes of Prelingual Hearing Loss 50% Genetic 50% Environmental 24% CMV intrauterine infection Other infections Rubella Bacterial Meningitis Toxoplasmosis NICU-related hypoxia Rh incompatibility ototoxic medications low birth weight 30% Syndromic (>400) 70% nonsyndromic (usually sensorineural) 22% autosomal dominant (29 loci) 77% autosomal recessive (30 loci) 1% X-linked (8 loci) <1% mitochondrial (2 loci)

  9. Syndromic Hearing Loss Alport Charcot-Marie-Tooth Goldenhar Jervell and Lange-Nielsen Mitochondrial disorders Neurofibromatosis Norrie Disease Pendred Treacher Collins Stickler Usher Waardenburg Vohwinkle

  10. Risk Factors for Hearing Loss In utero infection CMV, Herpes, HIV, Rubella, Syphilis In utero exposure to ototoxic drugs Aminoglycosides, Alcohol, Cocaine Intrauterine growth restriction Premature birth Low birthweight Neonatal bacterial meningitis Hyperbilirubinemia Mechanical ventilation Head trauma Recurrent or persistent otitis media Treatment with aminoglycoside antibiotics Family History , Genetics

  11. Causes of Hearing Loss Do other genetic and/or environmental factors modify expression of hearing loss in syndromes? Gene-environment interactions?

  12. Level 2 Research – Etiology of Hearing Loss in Infants and Young Children Cases: Infants with a permanent hearing loss identified through the universal newborn hearing screen; Children who passed the screen at birth but are diagnosed with hearing loss before the age of 3

  13. Level 2 Research – Etiology of Hearing Loss in Infants and Young Children Methods: collect information on known factors and family history clinical evaluation DNA analysis of GJB2 (Connexin 26), A1555G and A7445G (mitochondrial genes)

  14. Level 2 Research – Etiology of Hearing Loss in Infants and Young Children GA HI RI UT Estimated Eligible Participants Per Year 30 25 30 90 Estimated Total Participants Over 3 years 77 64 77 175 Estimated Total Participants = 448 Based on estimated 80% participation

  15. Level 2 Research – Etiology of Hearing Loss in Infants and Young Children Analyses: Description of factors associated with hearing loss in infants and young children Association of specific genes with hearing loss in infants and young children

  16. Level 2 Research – Etiology of Hearing Loss in Infants and Young Children Analyses: Interaction between genes and environment that cause hearing loss Gene-gene interactions that cause hearing loss

  17. Early Hearing Detection and Intervention …Promoting communication from birth

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