Despite the wide range of skin pigmentation in humans, little is known about its genetic basis in global populations. Examining ethnically diverse African genomes, we identify variants in or near SLC24A5, MFSD12, DDB1, TMEM138, OCA2 and HERC2 that are significantly associated with skin pigmentation. Genetic evidence indicates that the light pigmentation variant at SLC24A5 was introduced into East Africa by gene flow from non-Africans. At all other loci, variants associated with dark pigmentation in Africans are identical by descent in southern Asian and Australo-Melanesian populations. Functional analyses indicate that MFSD12 encodes a lysosomal protein that affects melanogenesis in zebrafish and mice, and that mutations in melanocyte-specific regulatory regions near DDB1/TMEM138 correlate with expression of UV response genes under selection in Eurasians.
Most genetic susceptibility to cutaneous melanoma remains to be discovered. Meta-analysis genome-wide association study (GWAS) of 36,760 melanoma cases (67% newly-genotyped) and 375,188 controls identified 54 significant loci with 68 independent SNPs. Analysis of risk estimates across geographical regions and host factors suggests the acral melanoma subtype is uniquely unrelated to pigmentation. Combining this meta-analysis with nevus count and hair color GWAS, and transcriptome association approaches, uncovered 31 potential secondary loci, for a total of 85 cutaneous melanoma susceptibility loci. These findings provide substantial insights into cutaneous melanoma genetic architecture, reinforcing the importance of nevogenesis, pigmentation, and telomere maintenance together with identifying potential new pathways for cutaneous melanoma pathogenesis.
Date palm (Phoenix dactylifera L.) is a cultivated woody plant species with agricultural and economic importance. Here we report a genome assembly for an elite variety (Khalas), which is 605.4 Mb in size and covers >90% of the genome (~671 Mb) and >96% of its genes (~41,660 genes). Genomic sequence analysis demonstrates that P. dactylifera experienced a clear genome-wide duplication after either ancient whole genome duplications or massive segmental duplications. Genetic diversity analysis indicates that its stress resistance and sugar metabolism-related genes tend to be enriched in the chromosomal regions where the density of single-nucleotide polymorphisms is relatively low. Using transcriptomic data, we also illustrate the date palm’s unique sugar metabolism that underlies fruit development and ripening. Our large-scale genomic and transcriptomic data pave the way for further genomic studies not only on P. dactylifera but also other Arecaceae plants.
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