Association of genetic variants with skin pigmentation phenotype among populations of west Maharashtra, India

2016 ◽  
Vol 28 (5) ◽  
pp. 610-618 ◽  
Author(s):  
Manjari Jonnalagadda ◽  
Heather Norton ◽  
Shantanu Ozarkar ◽  
Shaunak Kulkarni ◽  
Richa Ashma
Keyword(s):  
Genetic Variants ◽  
Skin Pigmentation ◽  
Pigmentation Phenotype

scholarly journals Environmental UVR Levels and Skin Pigmentation Gene Variants Associated with Folate and Homocysteine Levels in an Elderly Cohort

2020 ◽  
Vol 17 (5) ◽  
pp. 1545 ◽  
Author(s):  
Patrice Jones ◽  
Mark Lucock ◽  
Christopher J. Scarlett ◽  
Martin Veysey ◽  
Emma Beckett
Keyword(s):  
Genetic Variants ◽  
Biological Effect ◽  
Skin Pigmentation ◽  
Serum Folate ◽  
Gene Variants ◽  
Folate Status ◽  
Pigmentation Gene ◽  
Australian Cohort ◽  
Elderly Cohort ◽  
Multiple Chronic Diseases

Ultraviolet radiation (UVR) is a ubiquitous exposure which may contribute to decreased folate levels. Skin pigmentation mediates the biological effect of UVR exposure, but its relationship to folate levels is unexamined. Interactions may exist between UVR and pigmentation genes in determining folate status, which may, in turn, impact homocysteine levels, a potential risk factor for multiple chronic diseases. Therefore, independent and interactive influences of environmental UVR and genetic variants related to skin pigmentation (MC1R-rs1805007, IRF4-rs12203592 and HERC2-rs12913832) on folate (red blood cell (RBC) and serum) and homocysteine levels were examined in an elderly Australian cohort (n = 599). Genotypes were assessed by RT/RFLP-PCR, and UVR exposures were assessed as the accumulated erythemal dose rate accumulated over 4 months (4M-EDR). Multivariate analysis found significant negative associations between 4M-EDR and RBC folate (p < 0.001, β = −0.19), serum folate (p = 0.045, β = −0.08) and homocysteine levels (p < 0.001, β = −0.28). Significant associations between MC1R-rs1805007 and serum folate levels (p = 0.020), and IRF4-rs12203592 and homocysteine levels (p = 0.026) occurred but did not remain significant following corrections with confounders. No interactions between 4M-EDR and pigmentation variants in predicting folate/homocysteine levels were found. UVR levels and skin pigmentation-related variants are potential determinants of folate and homocysteine status, although, associations are mixed and complex, with further studies warranted.

scholarly journals The evolution of skin pigmentation associated variation in West Eurasia

2020 ◽  
Author(s):  
Dan Ju ◽  
Iain Mathieson
Keyword(s):  
Genetic Variants ◽  
Association Studies ◽  
Skin Pigmentation ◽  
Directional Selection ◽  
Genome Wide Association ◽  
Genome Wide Association Studies ◽  
Uk Biobank ◽  
Genome Wide ◽  
Light Skin ◽  
The Uk

AbstractSkin pigmentation is a classic example of a polygenic trait that has experienced directional selection in humans. Genome-wide association studies have identified well over a hundred pigmentation-associated loci, and genomic scans in present-day and ancient populations have identified selective sweeps for a small number of light pigmentation-associated alleles in Europeans. It is unclear whether selection has operated on all the genetic variation associated with skin pigmentation as opposed to just a small number of large-effect variants. Here, we address this question using ancient DNA from 1158 individuals from West Eurasia covering a period of 40,000 years combined with genome-wide association summary statistics from the UK Biobank. We find a robust signal of directional selection in ancient West Eurasians on skin pigmentation variants ascertained in the UK Biobank, but find this signal is driven mostly by a limited number of large-effect variants. Consistent with this observation, we find that a polygenic selection test in present-day populations fails to detect selection with the full set of variants; rather, only the top five show strong evidence of selection. Our data allow us to disentangle the effects of admixture and selection. Most notably, a large-effect variant at SLC24A5 was introduced to Europe by migrations of Neolithic farming populations but continued to be under selection post-admixture. This study shows that the response to selection for light skin pigmentation in West Eurasia was driven by a relatively small proportion of the variants that are associated with present-day phenotypic variation.SignificanceSome of the genes responsible for the evolution of light skin pigmentation in Europeans show signals of positive selection in present-day populations. Recently, genome-wide association studies have highlighted the highly polygenic nature of skin pigmentation. It is unclear whether selection has operated on all of these genetic variants or just a subset. By studying variation in over a thousand ancient genomes from West Eurasia covering 40,000 years we are able to study both the aggregate behavior of pigmentation-associated variants and the evolutionary history of individual variants. We find that the evolution of light skin pigmentation in Europeans was driven by frequency changes in a relatively small fraction of the genetic variants that are associated with variation in the trait today.

Skin pigmentation and genetic variants in an admixed Brazilian population of primarily European ancestry

2020 ◽  
Vol 134 (5) ◽  
pp. 1569-1579
Author(s):  
Jeppe D. Andersen ◽  
Olivia S. Meyer ◽  
Filipa Simão ◽  
Juliana Jannuzzi ◽  
Elizeu Carvalho ◽  
...  
Keyword(s):  
Genetic Variants ◽  
Skin Pigmentation ◽  
Brazilian Population ◽  
European Ancestry

scholarly journals Genetic Variability in Slovenian Cohort of Patients with Oculocutaneous Albinism

2021 ◽  
Vol 68 (3) ◽  
pp. 683-692
Author(s):  
Tinka Hovnik ◽  
Maruša Debeljak ◽  
Manca Tekavčič Pompe ◽  
Sara Bertok ◽  
Tadej Battelino ◽  
...  
Keyword(s):  
Genetic Variants ◽  
Diagnostic Yield ◽  
Skin Pigmentation ◽  
Great Majority ◽  
Oculocutaneous Albinism ◽  
European Ancestry ◽  
Syndrome Type ◽  
Targeted Next Generation Sequencing ◽  
Hermansky Pudlak Syndrome

Oculocutaneous albinism (OCA) is an inherited disorder affecting the visual system and skin pigmentation. Our aim was to evaluate genetic and clinical heterogeneity in a cohort of Slovenian paediatric patients with clinically suspected OCA using advanced molecular-genetics approach. In as much as 20 out of 25 patients, genetic variants explaining their clinical phenotype were identified. The great majority of patients (15/25) had genetic variants in TYR gene associated with OCA type 1, followed by variants in TYRP1, SLC45A2 and HPS1 genes causative for OCA3, OCA4 and Hermansky-Pudlak syndrome type 1, respectively. We concluded that OCA phenotype could not predict genotype and vice versa. Nevertheless, the diagnostic yield after targeted next generation sequencing (NGS) was 80% and proved to be affective in our paediatric cohort of patients with various degree of OCA. Even in 16 patients with normal complexion the diagnostic yield was 62,5%. Interestingly, we have identified a patient of white European ancestry with OCA3, which is an extremely rare report, and one patient with OCA due to the Hermansky-Pudlak syndrome type 1.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

Skin pigmentation and chlorpromazine

JAMA ◽  
1965 ◽  
Vol 194 (6) ◽  
pp. 670-672 ◽  
Author(s):  
A. S. Zelickson
Keyword(s):  
Skin Pigmentation
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