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Published byRaymond James Modified over 9 years ago
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Cystic fibrosis CF
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Cysticfibrosis Cystic fibrosis the most common autosomal recessive (AR) disorder among Caucasians chronic and progressive disease median at death is ~ 35 years OrgansAffectedby CF Organs Affected by CF Lung: thick accumulations of mucus, breathing difficulties, frequent resp. infectious, permanent lung damage frequent resp. infectious, permanent lung damage Pancreas: exocrine pancreatic insufficiency malabsorption of proteins and fats malabsorption of proteins and fats Liver: plugging of small bile ducts, cirrhosis GIT: intestinal obstruction-Meconium ileus (15-20% CF babies) Reproduction: improper formation of Vas deferens sterility (95% CF male) sterility (95% CF male) Skin: CF patients have salt crystal formation on their skin (sweat excessively)
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Molecular causation of CF NBD -nucleotide binding domains (ATP) R NBD1 NBD2 TM1 TM2 Cl - mutations in the CFTR gene CFTR gene coding for chloride channel protein: cystic fibrosis transmembrane conductance regulator – located on the plasma membrane of epithelial cells of the lungs, pancreas, sweat glands, and other tissues cAMP regulated chloride channel R -regulation domain (cAMPdep.) TM - transmembrane spanning domains lumen cytoplasm
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Mutation in the CFTRgene Mutation in the CFTR gene germinal mutations somatic mutations have not been described so far de novo mutation – rarely distribution of mutation shown population specificity
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F508del = delta F508 = ΔF508 the most common mutation among Caucasians(70%) deletion of three basepairs in exon 10 of DNA resulting in deletion of a Phe F508 from CFTR protein R NBD1 NBD2 TM1 TM2 Cl - … E N I I F G V S Y D… …..GAA AAT ATC ATC TTT GGT GTT TCC TAT GAT…. …..GAA AAT ATC ATT GGT GTT TCC TAT GAT…. … E N I I G V S Y D… 508
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Detection of ΔF508 mutation in CFTR gene This technique depends on the specificity of PCR primers 3 primers are made: General primer (C) Normal specific primer (N) Mutation specific primer (M ) M C TARGET SEQUENCE N X
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Detection of ΔF508 mutation in CFTR gene C/N C/M 121212 Homozygous No Mutation Heterozygous Carrier Homozygous for Mutation DNA sample in placed in 2 PCR tubes: Tube 1 contains primer C and primer N Tube 2 contains primer C and primer M
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Detection of ΔF508 mutation in CFTR gene STS gen (P3,4) – control of PCR process CFTR gen (P0,2) – general primer – primer specific to sequence without mutation STS gen (P3,4) – control of PCR process CFTR gen (P1,2) – general primer – primer specific to mutated sequence PCR Mix 1PCR Mix 1 PCR Mix 0PCR Mix 0 NC DNA marker Patient 1 2 3 + + + + - +
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Detection of ΔF508 mutation in CFTR gene PCR Mix 0 / Mix 1: Water 8.5µl Taq buffer 2.0µl dNTP mix 4.0µl Mg2+ (MgCl 2 ) 2.0µl DNA 2.0µl Primer mix M0 / M1 1.2µl Taq polymerase (on ice) 0.4 µl Total 20.0µl
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