Kazuo Umetsu

Distribution of the F374 Allele of the SLC45A2 (MATP) Gene and Founder‐Haplotype Analysis

The membrane‐associated transporter protein (MATP) plays an important role in melanin synthesis. The L374F mutation in the SLC45A2 gene encoding MATP has been suggested to be associated with skin colour in major human populations. In this study more detailed distribution of the F374 allele was investigated in 1649 unrelated subjects from 13 Eurasian populations and one African population. The highest allele frequency was observed in Germans (0.965); French and Italians showed somewhat lower frequencies; and Turks had an intermediate value (0.615). Indians and Bangladeshis from South Asia were characterized by low frequencies (0.147 and 0.059, respectively). We also found the F374 allele in some East and Southeast Asian populations, and explained this by admixture. Haplotype analysis revealed that the haplotype diversity was much lower in Germans than in Japanese, and suggest that the L374F mutation occurred only once in the ancestry of Caucasians. The large differences in distribution of the F374 allele and its haplotypes suggest that this allele may be an important factor in hypopigmentation in Caucasian populations.

MATP polymorphisms in Germans and Japanese: the L374F mutation as a population marker for Caucasoids

Inference of the population and ancestry to which an individual belongs is important in forensic individualization and personal identification. In this study, five polymorphisms of the membrane-associated transporter protein (MATP) gene were investigated in German and Japanese populations. The L374F mutation was present at an allele frequency as high as 0.96 in the German population, whereas it was completely absent in the Japanese population. This extreme difference in allele frequency suggests that the L374F mutation is valuable as a population and ancestry informative marker for Caucasoids.

Distribution of OCA2∗481Thr and OCA2∗615Arg, associated with hypopigmentation, in several additional populations

Two mutants, OCA2∗481Thr (c.1441G>A, p.Ala481Thr) and OCA2∗615Arg (c.1844A>G, p.His615Arg), in the OCA2 (oculocutaneous albinism type II) gene are associated with hypopigmentation in East Asians. Here, these two alleles were studied to assess the frequencies in five different populations. In addition, the allele frequency of OCA2∗615Arg was investigated in seven populations. Among a total of 24 global populations investigated, Oroqens in Heihe showed the highest frequency for OCA2∗481Thr (0.519), and among 26 populations, Han Chinese in Changsha showed the highest frequency for OCA2∗615Arg (0.673). This study confirmed that these two East Asian-specific alleles are characteristic of northern and central-southern East Asian populations.

Molecular basis of complement factor I (CFI) polymorphism: one of two polymorphic suballeles responsible for CFI A is Japanese-specific

AbstractIsoelectric focusing has revealed that human complement factor I (CFI) is controlled by two polymorphic alleles, CFI*A and CFI*B, and a few rare variant alleles. In this study the molecular basis of the CFI polymorphism was investigated in 174 Japanese. The CFI*A was divided into two suballeles, CFI*As (R201S) and CFI*Ah (R406H). CFI*Aj, a rare variant allele originating from CFI*Ah, had an additional mutation (R502L). The distribution of these three mutations and two registered SNPs was investigated in a total of 2,471 individuals in 20 populations from various areas, and six haplotypes were observed. Haplotype H3, which is characterized by CFI*As, was found only in Far East populations: the frequencies were about 0.03 in the main island of Japan and lower than 0.01 in Okinawa and Korea. Haplotype H5, characterized by CFI*Ah, prevailed almost exclusively in East Asians and was observed at the highest frequencies in southern Chinese Han and Thais. CFI*Ah must have arisen in a southeastern part of Asia and thereafter have spread to neighboring populations.

The human complement component C1R gene: the exon-intron structure and the molecular basis of allelic diversity.

Human C1r is a component of the complement system, which is a major mediator of innate immunity. In this study we investigated the exon‐intron organization of the human C1R gene, which spans 11 kb from the initiation codon to the stop codon, and is very similar in exon‐intron structure to the C1S gene. Six common and rare alleles, C1R*1, C1R*2, C1R*5, C1R*8, C1R*9, and C1R*13, were characterized by five mutations at amino acid positions 114, 135, 146, 167 and 244, in exons 4, 5 and 7 where the CUB1, EGF and CUB2 domains are encoded, respectively. A comparison with the cDNA of the mouse C1r gene showed that C1R*2is likely to be an ancestral allele. In addition, nine nucleotide substitutions and one length polymorphism were found in introns 2, 3, 4, 8 and 10.

A hypervariable STR polymorphism in the complement factor I (CFI) gene: Asian-specific alleles.

In this study, a short tandem repeat (STR) polymorphism in intron 7 of the human complement factor I (CFI) gene was studied in 637 DNA samples obtained from African, German, Thai, and Japanese populations and German and Japanese families. A total of 41 alleles were observed and classified into two groups, L and H, based on size differences. Group H, which consisted of 16 alleles, was observed only in Thai and Japanese populations at frequencies of 0.162 and 0.116, respectively, and was strongly associated with c.1217A in exon 11 (CFI*Ah). The heterozygosity values ranged from 0.89 in German to 0.93 in Thai populations. This STR would be a useful supplementary marker for forensic individualization.

Molecular Basis of ESD*5 and ESD*7 and Haplotype Analysis with New Polymorphisms in Introns

The two polymorphic alleles of esterase D (ESD), ESD*5 and ESD*7, are specific to Europeans and Asians, respectively. In this study the molecular basis was characterized: ESD*5, arising from ESD*1, has a G to A transition, resulting in Gly257 (GGT)→Asp(GAT); and ESD*7, originating from ESD*2, has an A to G transition, resulting in Asp231 (GAT)→ Gly(GGT). Glycine is also involved in the common ESD*1/ESD*2 polymorphism [Gly190 (GGA)→Glu(GAA)]. Haplotype analysis using a few novel intragenic polymorphisms showed strong associations among polymorphic sites, suggesting that recombination has been less frequent in the human ESD gene, although it spans about 25 kb from exon 1 to exon 10. A marked difference was observed in the distribution of haplotype frequencies between Germans and Japanese.

A hypervariable STR polymorphism in the CFI gene: Southern origin of East Asian-specific group H alleles

Previous studies of four populations revealed that a hypervariable short tandem repeat (iSTR) in intron 7 of the human complement factor I (CFI) gene on chromosome 4q was unique, with 17 possible East Asian-specific group H alleles observed at relatively high frequencies. To develop a deeper anthropological and forensic understanding of iSTR, 1161 additional individuals from 11 Asian populations were investigated. Group H alleles of iSTR and c.1217A allele of a SNP in exon 11 of the CFI gene were associated with each other and were almost entirely confined to East Asian populations. Han Chinese in Changsha, southern China, showed the highest frequency for East Asian-specific group H alleles (0.201) among 15 populations. Group H alleles were observed to decrease gradually from south to north in 11 East Asian populations. This expansion of group H alleles provides evidence that southern China and Southeast Asia are a hotspot of Asian diversity and a genetic reservoir of Asians after they entered East Asia. The expected heterozygosity values of iSTR ranged from 0.927 in Thais to 0.874 in Oroqens, higher than those of an STR in the fibrinogen alpha chain (FGA) gene on chromosome 4q. Thus, iSTR is a useful marker for anthropological and forensic genetics.

Haplotype analysis of seven Y-STRs (eleven loci) in two Japanese populations

We analyzed 11 Y-STR loci (DYS446, DYS447, DYS449, DYS450, DYS459a/b, DYS463 and DYS464a/b/c/d) in a total of 324 Japanese males from western and southern Japan. Gene diversity ranged from 0.958 at DYS464 in western Japan to 0.259 at DYS450 in southern Japan. A total of 272 different haplotypes were observed, of which 240 were found in single individuals. The overall haplotype diversity and discrimination capacity was 0.9982 and 0.8395, respectively.

The Structure and Diversity of α1-Acid Glycoprotein/Orosomucoid Gene in Africans

Human orosomucoid (ORM), or α1-acid glycoprotein, is known to be controlled by duplicated and triplicated genes on chromosome 9, encoding ORM1 and ORM2 proteins. In this study, the structure and diversity of the ORM gene were investigated in 16 Sub-Saharan Africans, who originated from widely dispersed locations in Africa. The duplicated ORM1-ORM2 gene was observed in all 16 samples. ORM1*S1(2), characterized by an ORM2 gene-specific sequence in intron 5, was common in Africans. Three Africans showed the duplication of the ORM1 gene. The organization of the triplicated ORM1A-ORM1B-ORM2 gene was established in two Africans. The recombination breakpoints resulting in the ORM1 duplication lay within a small genomic interval around exon 1 of the ORM1B gene. The duplication of the ORM2 gene reported previously was not detected in this population sample. Several single-nucleotide polymorphisms were observed in the ORM2 gene. The rearrangement of the ORM gene is likely to occur often in Africans.