Population genetic studies using isoelectric focussing in the Asian, Pacific and Australian area
Date
1984
Authors
Kamboh, Mohammad Ilyas
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Approximately four thousand blood samples from various ethnic groups
in the Asian, Pacific and Australian area have been subjected to isoelectric
focussing (IEF) to determine the subtyping of the proteinase
inhibitor (PI), transferrin (TF), vitamin D-binding protein (GC) and
phosphoglucomutase-1 (PGM1) systems and typing of the thyroxine-binding
globulin (TBG) system. Furthermore, the proposed physical association
between the PI and TBG proteins has been reexamined.
A considerable variation has been observed in the distribution of
the PI, TF, GC and PGM1 subtypes and new variants have also been
detected at these four loci. The mean heterozygosity per locus detected
by IEF varies from 0.40-0.54. This is much higher when compared to the
values of 0.13-0.23, obtained by conventional methods of electrophoresis.
Some common alleles at each of these four loci show interesting
patterns in their distribution. Maximum values of the PI*M2 allele are
encountered in Australian Aborigines and Papua New Guinea Highlanders,
whereas Asiatic Indians are characterized by having high frequencies of
the PI*M3 allele. The TF*C2 allele is present with a relatively high
frequency in Asian populations but, in contrast, Australian Aborigines,
Micronesians and Melanesians have a low prevalence of this allele. The
TF*C3 allele is present at polymorphic 1 evel only in Asiatic Indians.
For the GC locus, the highest frequency of GC*1S is found in
Asiatic Indians. By comparison, east and southeast Asians are unique
in having maximum values of the GC*1F allele. Most of the population
groups in the Australian-Pacific area have almost similar values for the
frequencies of the GC*1S and GC*1F alleles and these values are intermediate
between those observed in Asiatic Indians and in east Asians.
At the PGM1 locus the PGM1*1- allele has been detected with a high
frequency in Melanesians, Australian Aborigines and Indonesians from
the Lesser Sunda Islands, whereas, east Asians and Indian populations
IV
have approximately half this frequency. Moreover, Indian populations
are distinctive in having a higher frequency of the PGM1*2+ allele.
However, the lowest values of this allele are recorded in Micronesians.
The Polynesians, except for the Cook Islanders, are characterized by
having the highest frequency of the PGM1*2- allele. These values are
in contrast to the Papua New Guineans and Australian Aborigines where
the frequency of the PGM1*2- allele reaches its minimum values.
The gene frequency data from the PI, TF, GC and PGM1 loci have been
used to calculate Nei's genetic distance and to use the distance values
to demonstrate the genetic relationships between the Asian, Pacific and
Australian Aboriginal populations studied and then between these populations
and Europeans, Black Africans and Black Americans. The genetic
distances for each individual locus have been calculated first and then
the combined distances obtained from data for the four loci have been
computed. The genetic distances obtained from the four loci employing
the IEF data are then compared with those obtained using conventional
methods of electrophoresis. The data indicate that conventional
techniques do not permit adequate discrimination between the populations
since the clusters of populations formed are not supported by other types
of analyses. For example, Chinese appear to have close affinities with
Europeans, and Australian Aborigines are similar to Africans, whilst
Asiatic Indians have a close relationship with Fijians and Samoans.
However, the use of IEF makes possible discrimination between these populations
in accord with accepted views on relationships between peoples
in Asia, Europe and Africa. Here Black Africans and Black Americans are
at one extreme of the distribution whilst Australian Aborigines and Highlanders
in Papua New Guinea are at the other extreme: Europeans and
Asiatic Indians are closely related to one another.
A separate analysis was made also of the genetic relationships
between the north Indian caste groups. It shows that Arora and Rajput
cluster together strongly, and that genetically they are closer to
V
Brahmin than to Vaish or Scheduled Castes. In addition, the tribal
population of Soliga, in south India, is distinct from non-tribal populations.
However, the non-tribal south Indian series cluster closely
with the main caste groups in north India.
In the TBG system a genetically determined electrophoretic slow
variant, TBG S, which is indistinguishable from the variant found in
Black Africans, has been observed with polymorphic frequency in Melanesians
and Polynesians. This variant has also been observed sporadically
in Micronesians and in the Indonesian series from the Lesser Sunda
Islands. However, east Asians, Asiatic Indians and Australian Aborigines
were found to be monomorphic for TBG. Reexamination of the proposed
association between the PI and TBG proteins indicates that both
these proteins are clearly independent and the previously reported
association between PI and TBG appears to be an artefact of the method used.
Description
Keywords
Department of Human Biology, The Australian National University, John Curtin School of Medical Research, Asia, Pacific, Australia, blood, isoelectric focussing
Citation
Collections
Source
Type
Thesis (PhD)
Book Title
Entity type
Access Statement
License Rights
Restricted until
Downloads
File
Description