Topics and Speakers Michio Hirano, MD
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Synopsis
In this lecture, Dr Michio Hirano provides a comprehensive overview of classical and molecular genetics, beginning with Mendel's famous experiments and finishing with the current techniques of PCR (polymerase chain reaction) and DNA sequencing in investigating genetic disorders such as MNGIE disease (mitochondrial neurogastrointestinal encephalomyopathy) and Alzheimer's disease.
Classical genetics began with Gregor Mendel's work with peas which led to his discovery of two laws of genetics. The first law is the "law of segregation:" pair units of heredity, known as alleles, segregate during gamete (specialized germ cells that come together during fertilization) formation. The alleles are then randomly united during fertilization. The second law is the "law of independent assortment:" the allele pairs assert independently of each other, therefore resulting in traits that are transmitted independently of one another.
Molecular genetics began with the rediscovery of Mendel's work by Thomas Hunt Morgan in the early 20th century. Building upon Mendel, he discovered the chromosomal theory of inheritance: that each gene, a unit of heredity (an allele is a variation of that gene), is located in a particular chromosome (a single DNA molecule). Modern genetics, such as the discovery of the DNA double helix and the Human Genome Project, have shed surprising information about our makeup: two unrelated people have virtually the same genetic information; that is, 99.9% of the DNA between these two people will be identical. It is the remaining 0.1% which accounts not only for differences in phenotype (i.e., hair color, height, skin color) but also the genetic variance (i.e., genotype) that accounts for disease.
Dr Hirano concludes by explaining the technology behind PCR and DNA sequencing and how these techniques map out the disease loci of MNGIE in a long-term study of a family afflicted with this disease. He finishes with recent research findings that show that mutations in three genes may be related to the development of Alzheimer's.
