The population origin of an individual is often required to be determined from specimens left at a crime scene for estimating a suspect and individual identity. The melanocortin 1 receptor gene (MC1R) and P gene are associated with human pigmentation. Although there have been several reports that these genes are highly polymorphic in human populations, it is unclear if the allele variants can be used to estimate the population origin of an individual. We aimed to estimate the ethnic origin of a particular individual by using single nucleotide polymorphisms (SNPs). Four SNPs (MC1R gene: R163Q and P gene: IVS5+1001, IVS13+113 and H615R) were genotyped in 394 volunteers from 4 ethnically defined populations using a PCR-based assay. The results revealed that the allele variants were present with high frequency in Asian populations but were low in European and African populations. On the basis of these results, we defined a specific combination of a genotype (R163Q) and a diplotype group (IVS5+1001, IVS13+113 and H615R). This study indicates that the specific combination of a genotype and a diplotype group would be effective for estimating the population origin of an individual from a list of population groups.
[Show abstract][Hide abstract] ABSTRACT: Variation in human skin/hair pigmentation is due to varied amounts of eumelanin (brown/black melanins) and phaeomelanin (red/yellow melanins) produced by the melanocytes. The melanocortin 1 receptor (MC1R) is a regulator of eu- and phaeomelanin production in the melanocytes, and MC1R mutations causing coat color changes are known in many mammals. We have sequenced the MC1R gene in 121 individuals sampled from world populations with an emphasis on Asian populations. We found variation at five nonsynonymous sites (resulting in the variants Arg67Gln, Asp84Glu, Val92Met, Arg151Cys, and Arg163Gln), but at only one synonymous site (A942G). Interestingly, the human consensus protein sequence is observed in all 25 African individuals studied, but at lower frequencies in the other populations examined, especially in East and Southeast Asians. The Arg163Gln variant is absent in the Africans studied, almost absent in Europeans, and at a low frequency (7%) in Indians, but is at an exceptionally high frequency (70%) in East and Southeast Asians. The MC1R gene in common and pygmy chimpanzees, gorilla, orangutan, and baboon was sequenced to study the evolution of MC1R. The ancestral human MC1R sequence is identical to the human consensus protein sequence, while MC1R varies considerably among higher primates. A comparison of the rates of substitution in genes in the melanocortin receptor family indicates that MC1R has evolved the fastest. In addition, the nucleotide diversity at the MC1R locus is shown to be several times higher than the average nucleotide diversity in human populations, possibly due to diversifying selection.
[Show abstract][Hide abstract] ABSTRACT: We have determined the structure, nucleotide sequence, and polymorphisms of the human P gene. Mutations of the P gene result in type II oculocutaneous albinism (OCA2) in humans and pink-eyed dilution (p) in mice. We find that the human P gene is quite large, consisting of 25 exons spanning 250 to 600 kb in chromosome segment 15q11–q13. The P polypeptide appears to define a novel family of small molecule transporters and may be involved in transport of tyrosine, the precursor to melanin synthesis, within the melanocyte. These results provide the basis for analyses of patients with OCA2 and may point toward eventual pharmacologic treatment of this and related disorders of pigmentation.
[Show abstract][Hide abstract] ABSTRACT: We present a simple rapid reproducible polymerase chain reaction based technique, termed amplified product length polymorphism (APLP), as a new strategy for primer design for ABO genotyping. The method involves the use of primers differing in length and permits the identification of the major ABO genotypes (A1, A2, B, OA, OG, and O2) according to the molecular size of the allele-specific amplified products. Ten different primers designed to analyze the variations in nucleotide positions 261, 297, 796, 802, and 1059-1061 of cDNA are mixed in one reaction, and the amplified products are resolved on a polyacrylamide gel. Of eight PCR fragments (132 bp, 120 bp, 108 bp, 98 bp, 88 bp, 80 bp, 72 bp, and 64 bp), two to five are amplified in the reaction according to ABO genotypes. The new technique has been successfully applied to the genotyping of 221 peripheral blood samples from Japanese and Germans whose ABO phenotypes had previously been determined; a novel A allele (AG) was found in Japanese individuals.
Human Genetics 02/1997; 99(1):34-7. DOI:10.1007/s004390050306 · 4.82 Impact Factor
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