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Title of Thesis

Fareeha Zulfiqar
Institute/University/Department Details
University Of The Punjab
Molecular Biology
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
hereditary blindness, tunics of eye, vascular tunic, genome wide scan, lod score, retinitis pigmentosa, loci, photoreceptor dysfunction, drosophila

The last decade witnessed a rapid progress in studies of the genetics of retinitis pigmentosa (RP) There are over 70 loci that cause photoreceptor dysfunction or degeneration in drosophila and a similar number may be expected in humans (phelan and bak, 2000). So far, thirty- nine genetic loci responsible for nonsyndromic RP have been mapped in humans. Search for new RP loci/genes is imperative far a better understanding of the genetic and molecular bases of the visual cascade. The Pakistan population provides a valuable genetic resource for studies of retinitis pigmentosa because inbred families with many affected individuals are easily available.

In the present study. 65 consanguineous families with 2-5 sibships and 3-16 affected with nonysyndromic hereditary RP were enrolled Genomic DNA samples from blood samples of all the participating members of these families. The families with three or more affected were studied by linkage analysis. Genome wide scans were performed to map new RP loct and DNA sequence amylases done to fend new mutations in reported and new genes. As a result, RP phenotypes in six families linked to known RP loci. Mutational studies were carried out in two families for CNGAI and BBS2 genes. In family PKRP039 a 626- 627 del TA mutation in the CNGAL gene resulting in a predicted frame shift Ser209fs X26 was found segregating with RP. Analyses of PKRP014 revealed a novel Arg417Ter mutation in the BBS2 protein. The RP phenotype in remaining 59 families are found unlinked to any of the known RP causing loci, which support the nation that a large number loci/genes, remain undiscovered.

Genome wide linkage analyses revealed two new loci causing RP in the Pakistani population. Three families with autosomal recessive RP. PKRP006, PKRP040, and PKRP143, mapped to a 14.21 cM (21.19 Mb) region on chromosome 8q11. This region harbors gene responsible for autosomal dominant retinitis pigmentosa. RP. Sequence analyses of all the coding and nocoding exons of RPI show three different mutations segregating with RP with in these families, including two single base deletions. c. 7470delA and c. 8168delA resulting in a predicted frame shift and a 4bp insertion c 4377-4378ins TGAA. All these mutations are predicted to cause premature termination of the protein. This is a first report demonstrating the alleles of RP associated nonsyndromic recessively inherited pigmentosa.

A new RP cocus RP32 was mapped through the genome wide linkage analysis using the DNA sample from a multi-sibships consanguineous PKRP030 family segregating outosomal recessive RP phenotype cosegregates with polymorphic markers at Ip13.3-p21.2 defining a new locus for RP. This locus lies approximately 4.9cM (7.1Mb) from ABCA4, which is excluded from the linked region. Identification of this new locus will improve the understanding on the mechanism of vision transduction.

In conclusion this study reports the enrollment of 65 families with outosomal recessive retinitis pigmentosa, identification of two new mutations in the known RP genes. Mapping of two loci responsible for recessive RP and identification of recessive alleles of RPI gene.

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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
201.31 KB
2 1 Unit 1: Literature Survey 6-35
328.79 KB
  1.1 Structure Of The Eye And Mechanism Of Vision 6-16
  1.2 Structure Of Eye 7
  1.3 Three Layers, Or Tunics Of Eye 7
  1.4 Three Chambers Of Fluid 7
  1.5 Lens 9
  1.6 Tunics Of Eye 9
  1.7 The Fibrous Tunic: Sclera And Cornea 9
  1.8 The Vascular Tunic: Choroids, Iris And Ciliary Body 10
  1.9 The Neural Tunic: Retina 11
  1.10 Photoreceptors 13
  1.11 Photo ransduction Mechanism 14
  1.12 Visual Information Processing 15
  1.13 Retinitis Pigmentosa 17 €“ 28
  1.14 Genetic And Molecular Basis Of Genetics Of Retinitis Pigmentosa 29 €“ 35
3 2 Materials And Methods 37 €“ 60
344.63 KB
  2.1 Phases Of Work 37
  2.2 Search For Diseased Families 37
  2.3 Clinical Tests 38
  2.4 Dna Extraction 38
  2.5 Concenration Of Dna 40
  2.6 Preparation Of Replica Plates 40
  2.7 Exclusion Studies 40
  2.8 Genome Wide Scan 42
  2.9 Prepatation Of Samples For Abi 3100 Genetic Analyzer 44
  2.10 Dna Sequencing 45
  2.11 Automated Fluorescent Seqencers 46
  2.12 Data Organization Leads To Lod Score Calculation 48
  2.13 How To Run The Macros Of The Software 49
  2.14 Modules 50
  2.15 Lod Score 54
4 3 Linkage Analysis Of Pkrp Families 61 €“ 125
2795.56 KB
  3.1 Introduction 62
  3.2 Mutational Studies Of Pkrp039 And Pkrp014 68 €“ 92
  3.3 Identification Of A Novel Nonsyndromic Arrp Gene 93 €“ 109
  3.4 Genetic Mapping Of A New Locus Of Autosomal Recesive Rp Outside Abca 4 111 €“ 125
  3.5 Results 113
  3.6 Discussion 122
5 4 References 127 - 135
172.64 KB