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CYSTIC FIBROSIS (CF). Symptoms  Incorrect folding of the the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein results in its destruction.

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Presentation on theme: "CYSTIC FIBROSIS (CF). Symptoms  Incorrect folding of the the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein results in its destruction."— Presentation transcript:

1 CYSTIC FIBROSIS (CF)

2 Symptoms  Incorrect folding of the the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein results in its destruction  The cell membranes in epithelial cells of lungs, pancreas, colon and urinogenital tract lack chloride ion pores  Chloride and sodium imbalance results  Excessively salty sweat  Mucus secretion becomes thick and viscous. It cannot easily be cleared  Chronic lung congestion  Pancreatic obstruction  Liver damage and diabetes common amongst patients.  Median survival 19 years. © 2008 Paul Billiet ODWSODWS

3 Tests  Foetal proteins tested by amniocentesis  Sodium ion concentrations in sweat  Carriers tested using DNA probes for mutant allele © 2008 Paul Billiet ODWSODWS

4 Treatment  Physiotherapy helps reduce lung congestion  Pancreatic extracts can help digestive problems  Gene therapy being developed © 2008 Paul Billiet ODWSODWS

5 Frequency  1 in 2500 births in N Europe  1 person in 25 is heterozygous (carrier) © 2008 Paul Billiet ODWSODWS

6 Cause  A single mutant recessive allele of the CFTR gene  90% Caused by a deletion on the codon of position 508 (amino acid phenylalanine)  About 400 mutations of this gene are known  The CFTR gene is located on chromosome 7 © 2008 Paul Billiet ODWSODWS

7 NameNucleotide ChangeExonConsequence -816C->TC to T at-8165' flanking promoter mutation? -471delAGGdeletion of AGG from-471 5' flanking promoter mutation? M1VA to G at1331no translation initiation M1IG to T at1351Met to Ile at codon 1 S4XC to A at1431Ser to Stop at codon 4 174delAdeletion of A between frameshift 175insTinsertion of T after 175 1frameshift 185+1G->TG to T at 185+1intron 1mRNA splicing defect Some CFTR mutations © 2008 Paul Billiet ODWSODWS

8 Evolution  The high frequency of heterozygotes in N. Europe suggests a selective advantage  Some geneticists suggest it can protect against diseases like  BUT salt loss in sweat by CF carriers did not give them the advantage in hot climates  So CF frequency increased in temperate climates not in the tropics © 2008 Paul Billiet ODWSODWS


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