Selection on the Human Bitter Taste Gene, TAS2R16, inEurasian Populations

Bitter taste is one of the most important senses alerting humans to noxious foods. In gatherer communities, sensitivity to bitterness is presumably advantageous because of various noxious plants. TAS2R16 is the gene coding the taste receptor molecules for some of the most common toxins in plants. A previous study of this gene indicated selection has increased the frequency of a derived allele in this gene that arose before the human expansion out of Africa. We have applied a different methodology for detecting selection, the Long Range Haplotype (LRH) analysis, to TAS2R16 in a larger sampling of populations from around the world. The haplotype with the derived alleles at both the functional polymorphism and a polymorphism in the regulatory region of TAS2R16 showed evidence for recent positive selection in most of the Eurasian populations, though the highest selection signal occurs in Mbuti Pygmies, an African hunter-gatherer group. In Eurasia, only populations of Mesopotamia and the southeast coast of China have no signals of selection. The evidence of recent selection found in most Eurasian populations differs from the geographic pattern seen in the earlier study of selection. One can speculate that the difference may result from a gathering lifestyle extending into the most recent 10,000 yrs and the need to recognize newly encountered bitter natural toxins as populations expanded into new environments and the biota changes with the ending of the most recent ice age. Alternatively, the promoter region variant may be a marker for altered function beyond what the derived amino acid allele conferred

A Distinctive Pattern of Diversity for the TAS2R38 Gene in North Africa

The TAS2R38 gene is involved in bitter taste perception. This study documents the distinctive diversity patterns in Northern Africa of functional SNPs rs713598 and rs1726866 at the TAS2R38 locus and places those patterns in the context of global TAS2R38 diversity. We analyzed data previously genotyped with Taqman Applied Biosystem for rs713598 and rs1726866 for 375 unrelated subjects (305 Tunisians from seven locations: Mahdia, Sousse, Kesra, Nebeur, Kairouan, Smar and Kerkennah plus 70 Libyans). Data were analyzed to present haplotypes and genotypes and were compared to the data from worldwide populations. We provide information about TAS2R38 diversity in a part of the world that is relatively under-studied. Considering respectively the two SNPs rs713598 and rs1726866, the (C-A) nucleotide haplotype leading to PV amino acid haplotype is extremely rare almost everywhere, but it is relatively frequent (between 6% and 10%) in Northern Africa where it does coexist with the globally common haplotypes (PA, AA and AV). Given its higher frequency in Northern Africa, we propose the (C-A) haplotype as a biogeographic marker for forensic purposes

Mongolians in the Genetic Landscape of Central Asia: Exploring the Genetic Relations among Mongolians and Other World Populations

Genetic data on North Central Asian populations are underrepresented in the literature, especially autosomal markers. In the present study we use 812 single nucleotide polymorphisms that are distributed across all the human autosomes and that have been extensively studied at Yale to examine the affinities of two recently collected, samples of populations: rural and cosmopolitan Mongolians from Ulaanbaatar and nomadic, Turkic-speaking Tsaatan from Mongolia near the Siberian border. We compare these two populations to one another and to a global set of populations and discuss their relationships to New World populations. Specifically, we analyze data on 521 autosomal loci (single SNPs and multi-SNP haplotypes) studied on 57 populations representing all the major geographical regions of the world. We conclude that the North Central Asian populations we study are genetically distinct from all other populations in our study and may be close to the ancestral lineage leading to the New World populations

Dinucleotide polymorphism at the DXS1178 locus is tightly linked to PGK1 at Xq13

A polymorphic CA repeat (locus name DXS1178 ) was isolated from a 1-megabase YAC (OTCC) containing the OTC gene, located at Xp21.1. However, amplification in human-rodent hybrid cells and segregation analysis in three CEPH families mapped the DXS1178 locus at Xq13. The mapping ambiguity is apparently caused by the chimeric nature of the OTCC YAC clone.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47638/1/439_2004_Article_BF00208981.pd

One Large Kindred Excludes a Locus for Multiple Endocrine Neoplasia Type 2A from about 25% of the Human Autosomal Genetic Map

This report presents pairwise linkage results from our search for the locus of the gene (MEN2A) for the multiple endocrine neoplasia type 2A (MEN-2A) syndrome in one large kindred (the N kindred), clearly segregating for an autosomal dominant form. About 25% of the autosomal genome is excluded when these new results are combined with those we have published previously. The genetic markers employed are distributed across at least 19 of the 22 autosomes. Seven genetic markers whose chromosomal locations are not yet established have also been studied

Increasing the reference populations for the 55 AISNP panel: the need and benefits

Ancestry inference for an individual can only be as good as the reference populations with allele frequency data on the SNPs being used. If the most relevant ancestral population(s) does not have data available for the SNPs studied, then analyses based on DNA evidence may indicate a quite distantly related population, albeit one among the more closely related of the existing reference populations. We have added reference population allele frequencies for 14 additional population samples (with >1100 individuals studied) to the 125 population samples previously published for the Kidd Lab 55 AISNP panel. Allele frequencies are now publicly available for all 55 SNPs in ALFRED and FROG-kb for a total of 139 population samples. This Kidd Lab panel of 55 ancestry informative SNPs has been incorporated in commercial kits by both ThermoFisher Scientific and Illumina for massively parallel sequencing. Researchers employing those kits will find the enhanced set of reference populations useful

A global view of the OCA2-HERC2 region and pigmentation

Mutations in the gene OCA2 are responsible for oculocutaneous albinism type 2, but polymorphisms in and around OCA2 have also been associated with normal pigment variation. In Europeans, three haplotypes in the region have been shown to be associated with eye pigmentation and a missense SNP (rs1800407) has been associated with green/hazel eyes (Branicki et al. in Ann Hum Genet 73:160–170, 2009). In addition, a missense mutation (rs1800414) is a candidate for light skin pigmentation in East Asia (Yuasa et al. in Biochem Genet 45:535–542, 2007; Anno et al. in Int J Biol Sci 4, 2008). We have genotyped 3,432 individuals from 72 populations for 21 SNPs in the OCA2-HERC2 region including those previously associated with eye or skin pigmentation. We report that the blue-eye associated alleles at all three haplotypes were found at high frequencies in Europe; however, one is restricted to Europe and surrounding regions, while the other two are found at moderate to high frequencies throughout the world. We also observed that the derived allele of rs1800414 is essentially limited to East Asia where it is found at high frequencies. Long-range haplotype tests provide evidence of selection for the blue-eye allele at the three haplotyped systems but not for the green/hazel eye SNP allele. We also saw evidence of selection at the derived allele of rs1800414 in East Asia. Our data suggest that the haplotype restricted to Europe is the strongest marker for blue eyes globally and add further inferential evidence that the derived allele of rs1800414 is an East Asian skin pigmentation allele

Genome-wide association study of Tourette Syndrome

Tourette Syndrome (TS) is a developmental disorder that has one of the highest familial recurrence rates among neuropsychiatric diseases with complex inheritance. However, the identification of definitive TS susceptibility genes remains elusive. Here, we report the first genome-wide association study (GWAS) of TS in 1285 cases and 4964 ancestry-matched controls of European ancestry, including two European-derived population isolates, Ashkenazi Jews from North America and Israel, and French Canadians from Quebec, Canada. In a primary meta-analysis of GWAS data from these European ancestry samples, no markers achieved a genome-wide threshold of significance (p<5 × 10−8); the top signal was found in rs7868992 on chromosome 9q32 within COL27A1 (p=1.85 × 10−6). A secondary analysis including an additional 211 cases and 285 controls from two closely-related Latin-American population isolates from the Central Valley of Costa Rica and Antioquia, Colombia also identified rs7868992 as the top signal (p=3.6 × 10−7 for the combined sample of 1496 cases and 5249 controls following imputation with 1000 Genomes data). This study lays the groundwork for the eventual identification of common TS susceptibility variants in larger cohorts and helps to provide a more complete understanding of the full genetic architecture of this disorder

Genetic relationships of European, Mediterranean, and SW Asian populations using a panel of 55 AISNPs

The set of 55 ancestry informative SNPs (AISNPs) originally developed by the Kidd Lab has been studied on a large number of populations and continues to be applied to new population samples. The existing reference database of population samples allows the relationships of new population samples to be inferred on a global level. Analyses show that these autosomal markers constitute one of the better panels of AISNPs. Continuing to build this reference database enhances its value. Because more than half of the 25 ethnic groups recently studied with these AISNPs are from Southwest Asia and the Mediterranean region, we present here various analyses focused on populations from these regions along with selected reference populations from nearby regions where genotype data are available. Many of these ethnic groups have not been previously studied for forensic markers. Data on populations from other world regions have also been added to the database but are not included in these focused analyses. The new population samples added to ALFRED and FROG-kb increase the total to 164 population samples that have been studied for all 55 AISNPs