GWAS Study About Skin Color

DNA Unit 2 Lecture 4 GWAS Study about skin color: Melanin distribution among populations in Africa Manhattan plot shows a correlation of allele frequencies for pigmentation and UV exposure in global populations Shows frequency of the different SNPs, gene frequencies vary and distribution People with different skin color don’t differ don’t have dramatic different genes, there is polymorphism for both of G and A (SNPs associated with skin color, not distinct alleles) ●​ ●​ ●​ ●​ Africa has all the skin color genes, but only a subset shown in other countries Having a defect in melanin can affect one in many ways Identifying regions of the genome correlated with skin color Skin color is a continuous trait, and human populations are different in this trait ●​ Different genes for pigment for hair color and skin ●​ All capable of producing melanin unless albino ●​ Correlations between geography and skin color (darker = closer to the equator, has adaptive value to protect skin against UV that can damage DNA) while speculative reasons for lighter skin (could be useful or based on colonization) White supremacists chugging milk: “white people are more evolved, so they can digest milk without having lactose intolerance” Lactase Persistence (LP): Polysaccharide (starch) Disaccharides (lactose) which is digested by lactase enzyme ●​ All born with expressed lactase enzyme to drink milk to break down these sugars to use as energy in body ●​ Some lose this ability to break down the sugar and can’t digest lactose well ●​ Some have mutated and are lactase persistence, can express lactase later in life ○​ Global distribution of higher LP in Europe, W Asia and Africa ●​ Lactase Persistence was favored as milk could be used as a resource through life based on cultural and biological interactions in that time ●​ European Populations: T allele known for LP only common here ○​ There are 5 total that have independently evolved in diff countries Eugenics History: seeks to improve genetics, unifying theme across many fields Genger Mendal: peas experiment, but wasn’t applied to genetics until later ●​ Plant and animal breeders for superior quality, but applied to humans The early years: Francis Galton understood that individuals related to one another in a family tree also resembled one another ●​ Monozygotic and dizygotic studies, concluded 20% inheritable traits (under) ●​ Mutations that cause variation, along with continuous traits (height, weight) Charles Davenport: discovered Albinson through chicken studies American Eugenics: wanted to reduce/breed out the social burden of poorly defined traits (criminal, poverty) by restricting immigration and getting these individuals through sterilization laws, powered by race or poverty ●​ “Better baby” contests and propaganda about fit eugenic traits for “better race” ●​ Supported by Supreme Court “Buck v. Bell”: sterilize people against will like low IQ to prevent threat to society but also to next generations ○​ Virginia petition to sterilize patient due to low IQ as a threat to society UVA Eugenics: heritable genes promoted poverty, disease, inequality, and crime that could be reduced by improving the genetic stock ●​ Thomas Jefferson: own slaves, enlightenment viewpoint, ●​ Cabell: reconcile science with religion (racism), slavery was good for black/white ●​ Barringer: studied genetic differences and that mental problem were due to genetics, and that breeding with mixed people will create “bad genes” ●​ Alderman: promoted separated education, racial inequalities as social problem ●​ Jordan: dean of medical school and concluded that to cure people required eugenics. Saw Syliss in black who was a threat to the white race ●​ Lewis: chair of biology that promoted racism of Jewish Today: renamed UVA buildings after good influential people, and learning from past Nazi Germany Eugenics: used U.S. laws as a model for forced sterilization, holocaust Buck was deemed “defective” and sterlized (Eugenics still alive today) ●​ Favor all born with “tabula rasa” The blank slate, nature vs. nurture