Distribution of Gm and Km allotypes among five populations in China

The origin of the Japanese race based on genetic markers of immunoglobulin G

This review addresses the distribution of genetic markers of immunoglobulin G (Gm) among 130 Mongoloid populations in the world. These markers allowed the populations to be clearly divided into 2 groups, the northern and southern groups. The northern group is characterized by high frequencies of 2 marker genes, ag and ab3st, and an extremely low frequency of the marker gene afb1b3; and the southern group, in contrast, is indicated by a remarkably high frequency of afb1b3 and low frequencies of ag and ab3st. Based on the geographical distribution of the markers and gene flow of Gm ag and ab3st (northern Mongoloid marker genes) from northeast Asia to the Japanese archipelago, the Japanese population belongs basically to the northern Mongoloid group and is thus suggested to have originated in northeast Asia, most likely in the Baikal area of Siberia.

Evidence of a founder effect for the 235delC mutation of GJB2 (connexin 26) in east Asians

Mutations in the GJB2 gene encoding connexin 26 (Cx26) are a major cause of autosomal recessive and sporadic cases of congenital deafness in most populations. The 235delC mutation of GJB2 is the most frequent known mutation in some east Asian populations, with a carrier frequency of approximately 1%. In order to study the origin of 235delC among east Asians, we analyzed single-nucleotide polymorphisms (SNPs) within the coding region of GJB2 and flanking the 235delC mutation. We observed significant linkage disequilibrium between 235delC and five linked polymorphic markers, suggesting that 235delC arose from a common founder. The detection of 235delC only in east Asians, but not in Caucasians, and the small chromosomal interval of the shared haplotype suggest that 235delC is an ancient mutation that arose after the divergence of Mongoloids and Caucasians. Similarly, the finding that this mutation appears on a single haplotype provides no support for the possibility that recurrent mutation is the explanation for the high frequency of the allele.

Founder effect of the C9 R95X mutation in Orientals

A nonsense mutation at codon 95 (R95X) in the C9 gene is responsible for most Japanese C9 deficiency (C9D) cases, with a carrier frequency of 6.7%. Upon analysis of microsatellite markers and newly identified dinucleotide repeat number polymorphisms in the 3' flanking region of the C9 gene, a founder effect was demonstrated for the R95X mutation of the C9 gene in Japanese. Screening for the R95X mutation in Korean and Chinese individuals showed that the R95X carrier frequencies in Koreans and Chinese were 2.0% and 1.0%, respectively. Although homozygotes for the R95X mutation were not found in Korea or China, the shared haplotype of the dinucleotide repeat number polymorphisms appeared to be associated with the R95X mutation in the heterozygotes in Korea and China. The founder effect found in East Asians (Japanese, Koreans and Chinese) but not in Caucasians, as well as the haplotype sharing in only a small chromosomal interval, suggested that the R95X mutation of C9 gene was ancient and had occurred after the divergence of East Asians and Caucasians, and before migration of the Yayoi people to Japan. Since the mortality of meningococcal infections in complement-deficient patients is lower than that in normal individuals, a founder effect and a selective advantage in isolation might be the main reasons for the high frequency of the R95X mutation in Japan.

African diversity from the HLA point of view: influence of genetic drift, geography, linguistics, and natural selection

This study investigates the influence of different evolutionary factors on the patterns of human leukocyte antigen (HLA) genetic diversity within sub-Saharan Africa, and between Africa, Europe, and East Asia. This is done by comparing the significance of several statistics computed on equivalent population data sets tested for two HLA class II loci, DRB1 and DPB1, which strongly differ from each other by the shape of their allelic distributions. Similar results are found for the two loci concerning highly significant correlations between geographic and genetic distances at the world scale, high levels of genetic diversity within sub-Saharan Africa and East Asia, and low within Europe, and low genetic differentiations among the three broad continental areas, with no special divergence of Africa. On the other hand, DPB1 behaves as a neutral polymorphism, although a significant excess of heterozygotes is often observed for DRB1. Whereas the pattern observed for DPB1 is explained by geographic differentiations and genetic drift in isolated populations, balancing selection is likely to have prevented genetic differentiations among populations at the DRB1 locus. However, this selective effect did not disrupt the high correlation found between DRB1 and geography at the world scale, nor between DRB1 and linguistic differentiations at the African level.

Founder effect of a prevalent phenylketonuria mutation in the Oriental population

A missense mutation has been identified in the human phenylalanine hydroxylase [PAH; phenylalanine 4-monooxygenase; L-phenylalanine, tetrahydrobiopterin:oxygen oxidoreductase (4-hydroxylating), EC 1.14.16.1] gene in a Chinese patient with classic phenylketonuria (PKU). A G-to-C transition at the second base of codon 413 in exon 12 of the gene results in the substitution of Pro413 for Arg413 in the mutant protein. This mutation (R413P) results in negligible enzymatic activity when expressed in heterologous mammalian cells and is compatible with a classic PKU phenotype in the patient. Population genetic studies reveal that this mutation is tightly linked to restriction fragment length polymorphism haplotype 4, which is the predominant haplotype of the PAH locus in the Oriental population. It accounts for 13.8% of northern Chinese and 27% of Japanese PKU alleles, but it is rare in southern Chinese (2.2%) and is absent in the Caucasian population. The data demonstrate unambiguously that the mutation occurred after racial divergence of Orientals and Caucasians and suggest that the allele has spread throughout the Orient by a founder effect. Previous protein polymorphism studies in eastern Asia have led to the hypothesis that "northern Mongoloids" represented a founding population in Asia. Our results are compatible with this hypothesis in that the PKU mutation might have occurred in northern Mongoloids and subsequently spread to the Chinese and Japanese populations.

Blood genetic markers in the Chinese of two eastern provinces

A total of 205 Han Chinese from two eastern provinces (155 from Fujien and 50 from Hopeh) were tested for the distribution of six blood groups--A1A2BO, MN, Rhesus (CcDEe), Lewisa, Kell (Kk) and Fya--four serum proteins--albumin and haptoglobin types; transferrin and group-specific component subtypes--haemoglobin, and twelve red cell enzyme systems--glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, lactate and malate dehydrogenases; acid phosphatase, esterate-D, glyoxalase I, adenylate kinase, glucose-phosphate isomerase, phosphoglucomutase (locus 2), and superoxide dismutase types; and phosphoglucomutase (locus 1) subtypes. The frequencies of blood groups were more or less within the reported frequencies in the Chinese. However the frequency of le was much lower in the present series. The Chinese are characterized by low p1, Ro, k, le, and a high Fya in general. P2 was lacking in the Chinese. There were some differences in the blood group frequencies in the two provinces. The frequencies of Hp alleles; Tf and Gc subtypes show characteristic mongoloid features with high Hp1, TfD, and GcIF. The frequency of TFC2 was higher in the Fujien province than that in Hopeh. At the hemoglobin locus only one Hb AD was detected, while the frequency of the beta-thalassemia trait was 0.03. No red cell G6PD deficiency or variant was detected. The distribution of red cell enzymes showed Mongoloid characteristics with low PGDC, AK2, ESD1, GLO1, and higher pa. PGM1 subtypes also had Mongoloid characteristics with lower PGM2+ and higher PGM2-. The phenotypic distribution of all the fifteen polymorphic loci was at Hardy-Weinberg equilibrium in both the Chinese populations.

Characteristics of Mongoloid and neighboring populations based on the genetic markers of human immunoglobulins

Since the discovery in 1966 of the Gm ab3st gene, which characterizes Mongoloid populations, the distribution of allotypes of immunoglobulins (Gm) among Mongoloid populations scattered from Southeast Asia through East Asia to South America has been investigated, and the following conclusions can be drawn: 1. Mongoloid populations can be characterized by four Gm haplotypes, Gm ag, axg, ab3st, and afb1b3, and can be divided into two groups based on the analysis of genetic distances utilizing Gm haplotype frequency distributions: the first is a southern group characterized by a remarkably high frequency of Gm afb1b3 and a low frequency of Gm ag, and the second, a northern group characterized by a high frequency of both Gm ag and Gm ab3st but an extremely low frequency of Gm afb1b3. 2. Populations in China, mainly Han but including minority nationalities, show remarkable heterogeneity of Gm allotypes from north to south and contrast sharply to Korean and Japanese populations, which are considerably more homogenous with respect to these genetic markers. The center of dispersion of the Gm afb1b3 gene characterizing southern Mongoloids has been identified as the Guangxi and Yunnan area in the southwest of China. 3. The Gm ab3st gene, which is found with its the highest incidence among the northern Baikal Buriats, flows in all directions. However, this gene shows a precipitous drop from mainland China to Taiwan and Southeast Asia and from North to South America, although it is still found in high frequency among Eskimos, Koryaks, Yakuts, Tibetans, Olunchuns, Tungus, Koreans, Japanese, and Ainus. On the other hand, the gene was introduced into Huis, Uyghurs, Indians, Iranians, and spread as far as to include Hungarians and Sardinians in Italy. On the basis of these results, it is concluded that the Japanese race belongs to northern Mongoloids and that the origin of the Japanese race was in Siberia, and most likely in the Baikal area of the Soviet Union.

Distribution of Gm and Km allotypes among ten populations of Assam, India

Serum samples from ten endogamous populations of Assam, India-Brahmins, Kalitas, Kaibartas, Muslims, Ahoms, Karbis, Kacharis, Sonowals, Chutiyas, and Rajbanshis-were typed for G1m (1, 2, 3, 17), G3m (5, 10, 11, 13, 14, 15, 16, 21, 26), and Km (1). Among Brahmins, Kalitas, Kaibartas, Muslims, Ahoms, Sonowals, Chutiyas, and Rajbanshis, five different Gm haplotypes were found: Gm1,17;21,26; Gm1,17;10,11,13,15,16; Gm1,2,17;21,26; Gm1,3;5,10,11,13,14,26; and Gm3;5,10,11,13,14,26. Kacharis and Karbis show only four of these haplotypes: Gm3;5,10,11,13,14,26 is absent among them. The intergroup variability in the distribution of these haplotypes is considerable, which can be explained by the ethnohistory of these populations. Genetic distance analysis, in which five Chinese population samples were included, revealed the existence of three main clusters: 1) North and Central Chinese; 2) Kalitas, Kaibartas, Chutiyas, Rajbanshis, Muslims, and Brahmins; and 3) Ahoms, Sonowals, Kacharis, South Chinese, and Karbis. The clusters suggest some genetic relation between these four Assamese populations and South Chinese, which is again understandable considering the ethnohistory of the populations of Northeast India. In the Km system, too, a remarkable variability is seen in distribution of phenotype and allele frequency.