In 1951, two years before the double-helical structure of DNA was discovered, Barbara McClintock gave a lecture on her newest research into maize genetics, which revealed something truly surprising—certain genes were able to jump from one region of the genome to another. These jumping genes appeared to have a pronounced effect on the regions where they landed, disrupting and inactivating nearby genes. In maize (i.e., corn), these effects were easily visualized as changes in the color pattern of kernels over generations. Despite compelling evidence, McClintock’s lecture was met with confusion and open hostility from the scientific community because it conflicted…
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Last week we saw how the complex interplay of genetics and environment has impacted the inheritance of sickle-cell anemia. This week, I want to talk about a special subset of inherited diseases called sex-linked disorders. One of the most common sex-linked disorders is Duchenne muscular dystrophy (DMD), a debilitating muscular disorder linked to the X-chromosome. Sex-linked disorders, like DMD, come from genes in the sex chromosomes (X and Y in humans). Sex chromosomes are responsible for determining an individual’s biological sex, XX for female, XY for male (although there are other less common combinations that come from chromosomal aberrations—we’ll talk…
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