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Hello, my name is Yoshihito Niimura
from the University of Miyazaki, Japan.
The title of my talk is Major Gene Families
in Humans and Their Evolutionary History.
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This is the content of my talk.
First, I'd like to talk
about a multigene family.
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A multigene family is a group of genes that
have descended from a common ancestor and,
therefore, have similar functions
and similar DNA sequences.
Historically, a Japanese
geneticist Yoshinari Kuwada,
has mentioned the possibility of chromosome
duplication by observing the chromosomes of maize.
Later, Susumu Ohno published a book entitled
Evolution by Gene Duplication in 1970
and postulated that gene duplication
played a major role in evolution.
A gene duplication generates
two copies of the same gene.
In this situation, it is easier to gain an over function,
because one copy functions as a spare of the original gene.
Therefore, the other gene can alter its
function without losing its original function.
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Hemoglobin provides a classical
example of gene duplication.
It is well known that hemoglobin in red blood cells of
humans is composed of four subunits; two α and two β chains.
There are also γ and δ chains, which are mainly
used in fetuses and newborns, respectively.
In 1961, Ingram proposed that the genes encoding hemoglobin
α, β, γ and δ chains were generated by gene duplication.