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Title of Thesis

Sadaf Naz
Institute/University/Department Details
University of the Punjab/ National Centre Excellence in Molecular Biology
Molecular Biology
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
hearing pathway, deafness, syndromic deafness, phenocopy trait, syndromic loci, usher syndromes loci, tecta

To initiate a study on molecular characterization of non-syndromic recessive deafness in the Pakistani population, thirty-five consanguineous families of different ethnic groups were enrolled. Twenty-eight families with three or more affected individuals were analyzed for linkage to all known non-syndromic recessive deafness causing loci and seven of the unlinked families from this group were also screened for dominant and Usher syndromes loci. These screening studies led to the mapping of different deafness genes.

Fourteen families showed linkage to the known non-syndromic recessive deafness loci. Carriers of deafness genes were identified and information was provided to the families on request. DFNB3 was found to segregate in a maximum number of families (8.5%). Linkage analysis led to the recognition of Pendred syndrome in one family previously thought to have non-syndromic deafness. DNA sequencing analyses revealed novel mutations in the PDS gene for this and some other PDS linked families. These included 3 missense and one splice site mutation. A novel mutation in TECTA, 6037delG was identified in one of the families showing linkage to DFNB21. This is the second mutation in TECTA causing non-syndromic recessive deafness.

One family was linked to a non-syndromic recessive deafness locus at chromosomal interval 3q24-25. This appears to be a narrowed refinement of one of the DFNB15 loci and/or it may be an allelic variant to USH3. A novel non-syndromic deafness causing gene, DFNB29 was mapped to chromosome 21q22. DFNB8/10 were excluded as a case of deafness for this family. The candidate deafness gene interval was reduced to ~1.5 cM by screening this family for recombination events. Twelve families remained unlinked to the mapped chromosomal intervals for deafness genes, indicating that they may have some novel deafness causing genes.

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1503.96 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
145.59 KB
2 1 Introduction 1
61.31 KB
3 2 Literature Review 4
365.42 KB
  Structure Of The Ear 4
  Hearing Pathway 6
  Deafness 7
  Syndromic Deafness 8
  Non- Syndromic Deafness 8
  Genetic Classification 8
  Deafness As A Phenocopy Trait 9
  Linkage Analysis 10
  Localization Of Deafness Causing Genes 12
  Non- Syndromic Autosomal Recessive Loci 13
  Non- Syndromic Autosomal Dominant Loci 18
  Syndromic Loci 23
  Pendred Syndrome 23
  Usher Syndromes 24
4 3 Materials And Methods 27
194 KB
  Enrollment Of Families 27
  Enrollment Of Isolated Cases Of Deafness 27
  Collection Of Blood Samples From Unaffected Normal Controls 27
  Blood Collection And DNA Extraction 28
  Swabs Collection And DNA Extraction 28
  PCR For Microsatellites 29
  Separation Of Microsatellites By Page 30
  Genotyping 31
  LOD Score Calculations 34
  PCR For Exon Amplifications Of TECTA 34
  PCR Amplification Of PDS Exons 34
  Purifying TECTA Exons PCR Products 34
  Purifying PDS Exons PCR Products 35
  Sequencing 35
  PASA For TECTA Mutations 36
  PASA For PDS Mutation 38
5 4 Results 39
395.76 KB
  DFNBI Linked Families 39
  DFNB3 Linked Families 44
  PDS Linked Families And Sequencing Results 44
  DFNB6 Linked Family 50
  DFNB7/11 Linked Families 54
  DFNB8/10 Linked Family 54
  DFNB9 Linked Family 57
  DFNB15/USH3 Linked Family 57
  DFNB21 Linked Family And Sequencing Results 57
  DFNB21 Or DFNB24 Linked Family 61
  Mapping Of DFNB29 Novel Location On Chromosome 21 64
6 5 Discussion 73
205.17 KB
  Mapping Of Known Deafness Loci 73
  Novel Location 76
  Novel Mutations 76
7 6 References 89
278.77 KB