Natural Selection in Human Populations
• Natural Selection and Disease• The CCR5 gene• Gene is transcribed and translated to a surface
protein of T-helper cells. • Related to HIV (human immunodeficiency virus• Virus acquired from chimpanzees ca. 1930• Does no harm in chimpanzees.• Related to AIDS (acquired immune deficiency
syndrome)
Prevalence of HIV infection, ages 15-45
Increase over time in HIV prevalence in adults
Life cycle of HIV
Azidothymidine (AZT)treatment
Fast acquisition of resistance toAZT
• Some people are resistance to HIV
• CCR5 – delta 32 allele
• Sickle cell anemia and malaria
• Global incidence of malaria: 300-500 cases/year
• 1-3 million deaths/year
• Hemoglobin
• HbA HbS
• HbA/HbS = heterozygote advantage
HbA/HbS
sickle cell trait
HbS/HbS
sickle cell anemia
Frequency of HbS
Prevalence ofmalaria
Relationship between HbS and malarial impact
