Differences

This shows you the differences between two versions of the page.

--- chapter_19 [2024/09/10 18:10] – [Example of the effect of selection on dominant mutations:Huntington's disease] mike
+++ chapter_19 [2024/09/18 17:52] (current) – [Cystic fibrosis] mike
@@ Line 168: / Line 168: @@
 ==== Cystic fibrosis ====
-A second example of balanced polymorphism is cystic fibrosis, a disease caused by autosomal recessive mutations in the $CFTR$ gene (__c__ystic __f__ibrosis __t__ransmembrane conductance __r__egulator). Mutants disrupt Cl<sup>–</sup> transport, leading to disturbed osmotic balance across in epithelial cell layers of the lungs and intestine. The incidence in European populations is approx. 0.0025; therefore, $q=\sqrt{0.0025}=0.05$. This is a pretty high frequency! This is probably not due to either high mutation frequency or founder effect (many different $CTFR$ disease alleles have been found although 70% are the ΔF508 allele). Scientists believe that heterozygotes may be more resistant to bacterial infections that cause diarrhea such as typhoid or cholera and that this selection was imposed in densely populated European cities.
+A second example of balanced polymorphism is cystic fibrosis, a disease caused by autosomal recessive mutations in the $CFTR$ gene (__c__ystic __f__ibrosis __t__ransmembrane conductance __r__egulator). Mutations in $CTFR$ disrupt Cl<sup>–</sup> transport, leading to disturbed osmotic balance across in epithelial cell layers of the lungs and intestine. The incidence in European populations is approx. 0.0025; therefore, $q=\sqrt{0.0025}=0.05$. This is a pretty high frequency! This is probably not due to either high mutation frequency or founder effect (many different $CTFR$ disease alleles have been found although 70% are the ΔF508 allele). Scientists believe that heterozygotes may be more resistant to bacterial infections that cause diarrhea such as typhoid or cholera and that this selection was imposed in densely populated European cities.
 ==== Lysosomal storage disorders ====