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Introduction: Functional near-infrared spectroscopy (fNIRS) is a promising tool for studying brain activity, offering advantages such as portability and affordability. However, challenges in data collection persist due to factors like participant physiology, environmental light, and gross-motor movements, with limited literature on their impact on fNIRS signal quality. This study addresses four potentially influential factors-hair color, hair cleanliness, environmental light, and gross-motor movements-on fNIRS signal quality. Our aim is to raise awareness and offer insights for future fNIRS research., Methods: Six participants (4 Females, 2 Males) took part in four different experiments investigating the effects of hair color, hair cleanliness, environmental light, and gross-motor movements on fNIRS signal quality. Participants in Experiment 1, categorized by hair color, completed a finger-tapping task in a between-subjects block design. Signal quality was compared between each hair color. Participants in Experiments 2 and 3 completed a finger-tapping task in a within-subjects block design, with signal quality being compared across hair cleanliness (i.e., five consecutive days without washing the hair) and environmental light (i.e., sunlight, artificial light, no light, etc.), respectively. Experiment 4 assessed three gross-motor movements (i.e., walking, turning and nodding the head) in a within-subjects block design. Motor movements were then compared to resting blocks. Signal quality was evaluated using Scalp Coupling Index (SCI) measurements., Results: Lighter hair produced better signals than dark hair, while the impact of environmental light remains uncertain. Hair cleanliness showed no significant effects, but gross motor movements notably reduced signal quality., Conclusion: Our results suggest that hair color, environmental light, and gross-motor movements affect fNIRS signal quality while hair cleanliness does not. Nevertheless, future studies with larger sample sizes are warranted to fully understand these effects. To advance future research, comprehensive documentation of participant demographics and lab conditions, along with signal quality analyses, is essential., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Holmes et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

For unknow reasons, the melanocyte stem cell (McSC) system fails earlier than other adult stem cell populations 1 , which leads to hair greying in most humans and mice 2,3 . Current dogma states that McSCs are reserved in an undifferentiated state in the hair follicle niche, physically segregated from differentiated progeny that migrate away following cues of regenerative stimuli 4-8 . Here we show that most McSCs toggle between transit-amplifying and stem cell states for both self-renewal and generation of mature progeny, a mechanism fundamentally distinct from those of other self-renewing systems. Live imaging and single-cell RNA sequencing revealed that McSCs are mobile, translocating between hair follicle stem cell and transit-amplifying compartments where they reversibly enter distinct differentiation states governed by local microenvironmental cues (for example, WNT). Long-term lineage tracing demonstrated that the McSC system is maintained by reverted McSCs rather than by reserved stem cells inherently exempt from reversible changes. During ageing, there is accumulation of stranded McSCs that do not contribute to the regeneration of melanocyte progeny. These results identify a new model whereby dedifferentiation is integral to homeostatic stem cell maintenance and suggest that modulating McSC mobility may represent a new approach for the prevention of hair greying., (© 2023. The Author(s).)

There is a long-lasting debate about the possible functions of zebra stripes. According to one hypothesis, periodical convective air eddies form over sunlit zebra stripes which cool the body. However, the formation of such eddies has not been experimentally studied. Using schlieren imaging in the laboratory, we found: downwelling air streams do not form above the white stripes of light-heated smooth or hairy striped surfaces. The influence of stripes on the air stream formation (facilitating upwelling streams and hindering horizontal stream drift) is negligible higher than 1-2 cm above the surface. In calm weather, upwelling air streams might form above sunlit zebra stripes, however they are blown off by the weakest wind, or even by the slowest movement of the zebra. These results forcefully contradict the thermoregulation hypothesis involving air eddies., (© 2021. The Author(s).)

In mammals, the pigment molecule pheomelanin confers red and yellow color to hair, and the intensity of this coloration is caused by variation in the amount of pheomelanin. Domestic dogs exhibit a wide range of pheomelanin intensity, ranging from the white coat of the Samoyed to the deep red coat of the Irish Setter. While several genetic variants have been associated with specific coat intensity phenotypes in certain dog breeds, they do not explain the majority of phenotypic variation across breeds. In order to gain further insight into the extent of multigenicity and epistatic interactions underlying coat pheomelanin intensity in dogs, we leveraged a large dataset obtained via a direct-to-consumer canine genetic testing service. This consisted of genome-wide single nucleotide polymorphism (SNP) genotype data and owner-provided photos for 3,057 pheomelanic mixed breed and purebred dogs from 63 breeds and varieties spanning the full range of canine coat pheomelanin intensity. We first performed a genome-wide association study (GWAS) on 2,149 of these dogs to search for additional genetic variants that underlie intensity variation. GWAS identified five loci significantly associated with intensity, of which two (CFA15 29.8 Mb and CFA20 55.8 Mb) replicate previous findings and three (CFA2 74.7 Mb, CFA18 12.9 Mb, CFA21 10.9 Mb) have not previously been reported. In order to assess the combined predictive power of these loci across dog breeds, we used our GWAS data set to fit a linear model, which explained over 70% of variation in coat pheomelanin intensity in an independent validation dataset of 908 dogs. These results introduce three novel pheomelanin intensity loci, and further demonstrate the multigenic nature of coat pheomelanin intensity determination in domestic dogs., Competing Interests: AJ Slavney, MKJ, TK, TRN, AJ Sams and AR Boyko are employees of Embark Veterinary, Inc., that offers dog DNA testing as a commercial service. Adam R Boyko is a co-founder and partial owner of Embark Veterinary, Inc, and ARB, AJ Sams, AJ Slavney, MKJ and TK are co-inventors on US Provisional Patent application 63/004,204. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Objectives: In many primates, one of the most noticeable morphological developmental traits is the transition from natal fur and skin color to adult coloration. Studying the chronology and average age at such color transitions can be an easy and noninvasive method to (a) estimate the age of infants whose dates of birth were not observed, and (b) detect interindividual differences in the pace of development for infants with known birth dates., Materials and Methods: Using a combination of photographs and field observations from 73 infant chacma baboons (Papio ursinus) of known ages, we (a) scored the skin color of six different body parts from pink to gray, as well as the color of the fur from black to gray; (b) validated our method of age estimation using photographic and field observations on an independent subset of 22 infants with known date of birth; and (c) investigated ecological, social, and individual determinants of age-related variation in skin and fur color., Results: Our results show that transitions in skin color can be used to age infant chacma baboons less than 7 months old with accuracy (median number of days between actual and estimated age = 10, range = 0-86). We also reveal that food availability during the mother's pregnancy, but not during lactation, affects infant color-for-age and therefore acts as a predictor of developmental pace., Discussion: This study highlights the potential of monitoring within- and between-infant variation in color to estimate age when age is unknown, and developmental pace when age is known., (© 2020 Wiley Periodicals LLC.)

The effect of growth and parturition on hair cortisol concentrations of cattle was investigated. Plasma, saliva, and hair (black and white from the shoulders and hip) samples were collected from calves at 6 and 24 weeks old and from dairy cattle at the dry (1 and 2 months prepartum) and lactation (10, 50, 150, and 250 days postpartum) periods. Plasma and saliva cortisol concentrations were lower in 24-week-old calves than those of 6-week-old calves, and hair cortisol concentrations decreased regardless of color and position. In 6-week-old calves, hair cortisol concentrations differed between sampling positions, but this difference was not observed in 24-week-old calves. Plasma and saliva cortisol concentrations increased before parturition until 10 days postpartum then decreased until 50 days postpartum. The same trend was observed in the cortisol concentrations of white hair. Contrarily, cortisol concentrations in black hair remained unchanged and was lower than that in white hair. Hair cortisol concentration can vary greatly depending on the location on the body, hair color, cattle age, or parturition. When this method is used, all of the above factors must be considered., (© 2021 Japanese Society of Animal Science.)

About 1-2% of European population are redheaded, meaning they synthesize more pheomelanin than eumelanin, the main melanin pigment in humans. Several mutations could be responsible for this phenotype. It has been suggested that corresponding mutations spread in Europe due to a founder effect shaped either by a relaxation of selection for dark, UV-protective phenotypes or by sexual selection in favour of rare phenotypes. In our study, we investigated the levels of vitamin D precursor 25(OH)D3 (calcidiol) and folic acid in the blood serum of 73 redheaded and 130 non-redheaded individuals. In redheaded individuals, we found higher 25(OH)D3 concentrations and approximately the same folic acid concentrations as in non-redheaded subjects. 25(OH)D3 concentrations correlated with the intensity of hair redness measured by two spectrophotometric methods and estimated by participants themselves and by independent observers. In non-redheaded individuals, 25(OH)D3 levels covaried with the amount of sun exposure and intensity of suntan while in redheaded individuals, this was not the case. It suggests that increased 25(OH)D3 levels in redheaded individuals are due to differences in physiology rather than in behaviour. We also found that folic acid levels increased with age and the intensity of baldness and decreased with the frequency of visiting tanning salons. Our results suggest that the redheaded phenotype could be an evolutionary adaptation for sufficient photosynthesis of provitamin D in conditions of low intensity of UVB radiation in central and northern parts of Europe., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

During the last two decades, hair cortisol concentration (HCC) has proven to be a promising marker for the evaluation of increased hypothalamic-pituitary-adrenal axis activity caused by repeated or long-term stressful conditions. A minimally invasive sampling procedure, simple storage and the retrospective characteristic of one hair sample are reasons why HCC is increasingly used not only in human medicine but also in animal welfare research. However, before applying HCC as a reliable indicator for stress, it is important to investigate potential influencing factors in addition to stressors in the species of interest. Thus, the aim of our study was to elucidate the impact of age, sex, hair color, body region, age of hair segments and season of hair sampling on HCC in pigs and cattle. Hair samples were taken by electric clippers and analyzed by ELISA after extraction. Our results show similar effects of influencing factors in both species. Significantly increased HCCs were found in young animals after birth compared with older age groups. In addition, HCCs were significantly higher in samples obtained from the tail tip in comparison with samples from the shoulder, neck and back regions, in black hair compared with white hair and in distal hair segments. Season had an impact on HCC only in cattle, which exhibited higher levels in winter than in summer. In conclusion, age, body region, hair color, hair segment and season affect hair cortisol concentrations and should be considered and controlled for when HCC is applied as a potential stress indicator in pigs and cattle. In addition, further research is necessary to elucidate the mechanisms by which cortisol is incorporated into the hair shaft., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Empirical and anecdotal evidence has associated stress with accelerated hair greying (formation of unpigmented hairs) 1,2 , but so far there has been little scientific validation of this link. Here we report that, in mice, acute stress leads to hair greying through the fast depletion of melanocyte stem cells. Using a combination of adrenalectomy, denervation, chemogenetics 3,4 , cell ablation and knockout of the adrenergic receptor specifically in melanocyte stem cells, we find that the stress-induced loss of melanocyte stem cells is independent of immune attack or adrenal stress hormones. Instead, hair greying results from activation of the sympathetic nerves that innervate the melanocyte stem-cell niche. Under conditions of stress, the activation of these sympathetic nerves leads to burst release of the neurotransmitter noradrenaline (also known as norepinephrine). This causes quiescent melanocyte stem cells to proliferate rapidly, and is followed by their differentiation, migration and permanent depletion from the niche. Transient suppression of the proliferation of melanocyte stem cells prevents stress-induced hair greying. Our study demonstrates that neuronal activity that is induced by acute stress can drive a rapid and permanent loss of somatic stem cells, and illustrates an example in which the maintenance of somatic stem cells is directly influenced by the overall physiological state of the organism.

Hair follicular keratinocyte stem cells (HFKSC) which provide a functional niche for melanocyte stem cells (MSC) are the primary target of hair graying. However, little research has been done on anti-hair graying medicines targeting HFKSC. We focused on Eriodictyon angustifolium (Ea), which reduces human hair graying when applied topically. To investigate the protective effect of dietary Ea tea (EaT) on hair pigmentation, we used an acute mouse model of hair graying that mimics X-ray-induced DNA damage associated with age-related hair graying. Our results suggest that dietary EaT maintained the niche HFKSC function against X-ray-induced DNA damage and hair graying. These results indicate that dietary EaT may prevent age-related hair graying and serve as an anti-hair graying herbal medicine.

In a previous study, we showed that the size of melanosomes isolated from Japanese female hairs enlarges with age, and this affects the hair color. In this study, we analyzed the age-dependent changes in hair melanin in order to further explore the factors related to hair color changing by aging. A significant positive correlation with age was found in the total melanin amount (TM) and the mol% of 5,6-dihydroxyindole (DHI) units, while no correlation was found in pheomelanin mol%. TM showed significant correlations with hair color parameters and the melanosome volume, suggesting that hair color darkening by aging is caused by the increase in TM due to the enlargement of the size of melanosome. From the measurement of absorbance spectra on synthetic eumelanins with different ratios of DHI and 5,6-dihydroxyindole-2-carboxylic acid (DHICA), we found that the increase in DHI mol% also contributes to the darkening of hair color by aging. In addition, the level of pyrrole-2,3-dicarboxylic acid (PDCA), a marker of DHI melanin, showed a significant negative correlation with the aspect ratio of melanosome, suggesting a contribution of DHI melanin to the change in melanosome morphology by aging.

Background: Objective determination of skin color has become an essential requirement in managing pigmentary disorders including vitiligo. The readings of available devices can be influenced by factors such as surrounding temperature, vasodilation/constriction, and skin surface properties. Our aim was to investigate the influence of hair color and length, skin stretching, incomplete contact of the device with the skin, and the pressure with which the device is applied to the test area on skin color determination., Materials and Methods: Dermacatch® was used to determine the influence of hair color and length in 30 vitiligo patients, and of wrinkles, incomplete contact of the device with the skin and pressure of the device on the test area in 30 healthy volunteers on melanin and erythema indices measured by the device., Results: Melanin index was significantly higher in lesions with black hair compared to lesions with white hair (P < 0.001) and the MI significantly decreased when the black hair was shaved (P < 0.001) and when the skin over the test area was stretched (P < 0.001). Incomplete contact of the device with the test area led to significantly higher MI (P < 0.001) and lower EI (P < 0.001). Meanwhile, high pressure induced by the device on the test area led to significantly lower MI (P < 0.001) and significantly higher EI (P < 0.001)., Conclusions: Factors influencing the readings of devices used for objective determination of skin color have to be taken consideration to ensure accuracy of the measurements done., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: The main objective of this study was to determine the lipid profile of brown and white Caucasian hair fibres and the effects of lipids on the properties of fibres., Materials and Methods: To determine the structures of white and brown hair lipid bilayers, cross sections of fibres of both hair types were examined using synchrotron-based μ-FTIR mapping. Dynamic vapour sorption (DVS) analyses were also performed to determine the differences in the barrier function of both fibres., Results: Spatial identification of lipids showed that a great amount of lipids was present in the medulla of fibres of both hair types, but important differences were also observed between cuticles of the different fibres. The cuticle of a white hair fibre showed a significant decrease in its lipid content, but did not show differences in the lateral packing order with respect to the cuticle of a brown hair fibre. The cortex and medulla of the white hair fibre also exhibited a significant decrease in its lipid content but with a higher lateral packing order than brown hair. Using DVS analysis, it was found that the water dynamics of white hair fibres differed from those of brown hair fibres, showing a decrease in their total capacity to absorb water and an increase in the velocity of the exchange of water with the environment., Conclusion: The results of both techniques demonstrated a high correlation between the characteristics of the lipids located in the cuticle and the water dynamics of the fibres., (© 2019 John Wiley & Sons A/S . Published by John Wiley & Sons Ltd.)

Hair pigmentation is regulated by follicular melanogenesis, in which the process consists of melanin formation and transfer to keratinocytes in the hair shaft. Human hair follicles contain two types of melanin: the brown-black eumelanin and yellow-red pheomelanin. Eumelanin is commonly present in black and brown hair while pheomelanin is found in auburn and blonde hair. Hair follicle melanogenesis is under cyclical control and is concurrently coupled to hair growth. Many factors including intrinsic and extrinsic factors affect the follicular melanogenesis. Though many studies have been conducted to identify the pathogenesis and regulation of hair pigmentation, the etiology of canities and hair pigmentation is still unclear. The pathogenesis of canities or gray hair is believed to occur either from insufficient melanin formation due to melanocyte degeneration or a defect in melanosomal transfer. Canities is an aging sign which often interferes with one's socio-cultural adjustment. On the other hand, premature canities correlate with diseases such as osteopenia and cardiovascular disease. Risk factors associated with canities are not only genetic but also external causes. For example, smoking, alcohol consumption, and stress are among the most common factors. Camouflage techniques are still used as the primary treatment of canities. Further treatments for canities are being developed to achieve the true reversal of hair pigmentation., (© 2019 The International Society of Dermatology.)

Angiotensin II (AngII) regulates pigment synthesis by tyrosinase in melanocytes. To evaluate the association between AngII and coat color formation, we detected the expression distribution of AngII in white and black sheep skins by LC-ESI-MS/MS, western blot, quantitative real-time-PCR (qPCR) and distribution of AngII by immunohistochemistry.Liquid chromatography-electrospray ionization tandem MS (LC-ESI-MS/MS) results showed that AngII was found in white and black skin tissues of sheep. Western blot results verified the LC-ESI-MS/MS results and suggested that AngII was expressed at significantly higher levels in black sheep skins compared with the white sheep skins. Quantitative real time PCR (qRT-PCR) results also revealed that the expression level of AngII mRNA was higher in black sheep skins than that in white sheep skins. Immunohistochemical analysis further demonstrated that AngII protein was localized in the hair bulb and outer root sheath of hair follicle in sheep. In summary, protein and transcripts exhibited the same expression pattern in white and black sheep skins. Furthermore, the expressions of AngII in the hair bulb and outer root sheath of black sheep were stronger than those in white sheep. These results suggested that AngII functions in sheep coat color regulation and offer a novel insight for further investigation on the role of AngII in the coat color formation in sheep., (Copyright © 2019. Published by Elsevier GmbH.)

Melanocyte stem cells (McSCs) are the undifferentiated melanocytic cells of the mammalian hair follicle (HF) responsible for recurrent generation of a large number of differentiated melanocytes during each HF cycle. HF McSCs reside in both the CD34+ bulge/lower permanent portion (LPP) and the CD34- secondary hair germ (SHG) regions of the HF during telogen. Using Dct-H2BGFP mice, we separate bulge/LPP and SHG McSCs using FACS with GFP and anti-CD34 to show that these two subsets of McSCs are functionally distinct. Genome-wide expression profiling results support the distinct nature of these populations, with CD34- McSCs exhibiting higher expression of melanocyte differentiation genes and with CD34+ McSCs demonstrating a profile more consistent with a neural crest stem cell. In culture and in vivo, CD34- McSCs regenerate pigmentation more efficiently whereas CD34+ McSCs selectively exhibit the ability to myelinate neurons. CD34+ McSCs, and their counterparts in human skin, may be useful for myelinating neurons in vivo, leading to new therapeutic opportunities for demyelinating diseases and traumatic nerve injury., Competing Interests: The authors declare no competing financial interests.

Vulnerable animals to heat stress have been described as ones with dark or black hides due to increasing absorption of solar radiation. The effect of coat color in pluriparous contemporary Holstein cows in a hot environment (mean annual temperature 24.6 °C), on body surface temperature (infrared thermography), physiological and hematological variables as well as milk yield and reproductive performance was assessed using 178 Holstein pluriparous cows (74 predominantly white and 104 predominantly black). Data were collected in the morning and afternoon in July (mean temperature-humidity index 82 units). Body condition score at mid-lactation (128 ± 32 days in milk at the start of the experiment) was higher (P < 0.01) in predominantly white than in black cows (3.3 vs. 3.2). Respiration rate did not differ between groups (72 ± 23 vs. 73 ± 20 breaths/min for white and black cows, respectively, sampling time combined). In contrast, rectal temperature of black cows was 0.1 °C higher (P ≤ 0.01) than white cows, regardless of sampling time. The only significant hematologic change was a slight increase in mean corpuscular volume in black cows (54.7 fL, P < 0.01) compared to white cows (53.8 fL), but it remained within the reference range. Differences due to coat color did not alter body surface temperatures at any time of the day. Conception rates, services per conception, calving intervals and fetal losses were not associated with hair coat color, but cows with predominantly white coat produced 394 kg more (P < 0.01) fat-corrected milk in 305 days compared to cows with predominantly black coat. It was concluded that in this hot-arid environment with cows housed in facilities with extensive cooling, black hair coat moderately reduces 305-d milk yield without affecting milk composition, body surface temperature, and reproductive performance., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Poor adherence to inhaled drug therapy in individuals with asthma and/or chronic obstructive pulmonary disease (COPD) may be associated with suboptimal therapeutic outcomes. Measurement of drug residues in hair samples has been employed to assess oral medication use over time. Here, we test the feasibility of analyzing hair samples from patients with asthma and/or COPD for assessing adherence to prescribed inhaled medication., Methods: In total, 200 male and female subjects, ≥ 18 years of age, with stable asthma and/or COPD who were receiving an acceptable standard of care daily inhaled product consistently, were recruited. Head hair samples were taken during a single visit to the clinical site and grouped by hair color according to the Fischer-Saller scale. Drug residues were extracted from milled hair samples using solid-phase extraction and analyzed using liquid chromatography-tandem mass spectrometry., Results: Inhaled drugs were detected in hair for 72% of subjects from whom it was possible to analyze hair samples (n = 157/200). Most hair samples obtained from subjects receiving formoterol or vilanterol had amounts of drug present that allowed determination of a quantifiable concentration, and demonstrated a dose response. Drugs were detected in all hair colors, with higher concentrations of formoterol observed in dark-haired versus light-haired individuals., Conclusions: This is the first study to demonstrate that inhaled medication can be measured in hair samples from subjects with asthma and/or COPD. The results show that hair drug concentration data could potentially provide a record of historical adherence to inhaled therapeutics., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Hair graying and hair loss are prominent and common characteristics of the elderly population. In some individuals these processes can significantly impact their quality of life, leading to depression, anxiety and other serious mental health problems. Accordingly, there has been much interest in understanding the complex physiological changes within the hair follicle in the aging individual. It is now known that hair follicles represent a prototypical stem cell niche, where both micro- and macroenvironmental influences are integrated alongside stem cell-stem cell and stem cell-stem niche interactions to determine hair growth or hair follicle senescence. Recent studies have identified imbalanced stem cell differentiation and altered stem cell activity as important factors during hair loss, indicating new avenues for the development of therapeutic agents to stimulate hair growth. Here, we pull together the latest findings on the hair follicle stem cell niche and the multifactorial interactions underlying the various forms of hair loss., (© 2017 Japanese Dermatological Association.)

Purpose: This review evaluates the effects of γ-rays on the regeneration of murine hair follicles in the natural hair cycle. A series of studies were performed to investigate this issue, in which the whole bodies of C57BL/10JHir mice in the 1st telogen phase of the hair cycle were irradiated with γ-rays., Results: The dermis of the irradiated skin showed a decrease in hair follicle density and induction of curved hair follicles along with the presence of white hairs and hypopigmented hair bulbs in the 2nd and 3rd anagen phases. An increased frequency of hypopigmented hair bulbs was still observed in the later hair cycle at postnatal day 200. There was no significant difference in the number of stem cells in the hair bulge region between control and irradiated skin., Conclusions: These results show that the effects of γ-rays on the pigmentation of murine hair follicles are persistently carried over to later hair cycles, although those on the number and structure of hair follicles appear to be hidden by the effects of aging. Our findings may be important for understanding the mechanisms of the actions of stem cells on hair regeneration in connection with age-related phenotypes.

Owing to the scanty evidence on usefulness of information of appearance of gray hair for age estimation, this study was conducted to estimate age based on the appearance of gray hair on different body sites in a sample of autopsy cases in Sri Lanka. A descriptive cross-sectional study was conducted in Teaching Hospital-Kurunegala during 2011 to 2013. Based on the pattern of the presence of gray hair in different body sites, six stages of gray hair were computed. The analysis 1155 autopsy cases revealed strong, positive correlations between age and appearance of gray hair in head, mustache, beard, and pubic area among males and strong, positive correlations between age and the appearance of gray hair in head and pubic area among females (p < 0.01). Our findings demonstrate the value of information of appearance of gray hair for age estimation in the field of forensic science., (© 2016 American Academy of Forensic Sciences.)

Intra-specific color variation is often underestimated by researchers, and among mammals, intra-specific differences in coloration are poorly documented for most species. The main goal of this study was to apply an objective color measurement methodology to the study of a specific problem: the detection, if any, of patterns of changes in the fur color of specimens of Akodon budini in relation to biological (i.e., sex) and environmental (i.e., season) variables. We hypothesize that coat color will be more homogeneous in males than in females and that coat color will be darker in winter than in summer, the latter being orange. We measured the pelage color on five points over the dorsal surface of 26 A. budini museum specimens using a spectroradiometer and a diffuse illumination cabin. We used Principal Component Analysis to describe the association between the color variables, sex and season, and each of the observations. We then used general linear models of Analysis of Variance to examine relationships between color data, season, and sex. The results clearly confirm the hypothesis related to seasonal coat color change but do not directly confirm the hypothesis related to changes in coat color in relation to sex, and we show the complexity of the studied pattern. In conclusion, undoubtedly, the studied variables should accordingly be considered when studying the coloration of specimens for characterization, identification and discrimination of different taxonomic units based on color.

The deleterious effects of heat stress on animal health are being increasingly recognized. This study aimed to determine hair cortisol (HC) and serotonin levels in lactating Holstein cows under heat stress conditions with different coat and hair-cut color. Forty-five multiparous lactating Holstein cows (days in milk = 130 ± 47, body weight = 753 ± 85 kg) were divided to two main groups of over 80% black coat color (BC) and over 85% white coat color (WC) visually observed based on registry certificates and subdividing to black hair sample (BH) and white hair samples (WH) in 2 × 2 factorial arrangements. Hair samples were taken from the forehead of the individuals. Higher HC levels were observed in BC than WC cows (P < 0.05). No differences were found in HC levels between BH and WH groups (P > 0.05). Serotonin levels showed no difference between BC and WC (P > 0.05). Interaction between coat color and hair color was not significant (P > 0.05). The cortisol levels in hair are not affected by pigmentation. However, pigmentation within the coat alters cortisol levels. In conclusion, white coat color retains less cortisol than the black coat. Therefore, white coats are preferable for dairy cows under heat stress conditions., (© 2016 Japanese Society of Animal Science.)

Background/purpose: Oxidative hair dyes can damage the hair, since these chemical procedures are involved to change the fiber structure and therefore changes in their mechanical and surface properties. Evaluate and compare the effect of the two colors of oxidative hair dye emulsions on Caucasian hair. This research analyzed the Dark brown hair untreated (I); Dark brown hair treated with light brown dye (II); Dark brown hair treated with light blond dye (III); Light blond hair untreated (IV); Light blond hair treated with light brown dye (V); Light blond hair treated with light blond dye (VI) on Caucasian hair., Methods: The hair samples were submitted to breaking strength, color, and optical coherence tomography (OCT) analysis., Results: For the breaking strength assay no presented statistically significant differences between treatments. The parameters of color and brightness can differ in some hair dye formulations, but also the hair type can respond differently. The OCT images of the sample I and IV was possible observed, clearly Medulla and Cortex, which was not observed clearly after treatment with both oxidative hair dye colors., Conclusion: Based on the results, the oxidative hair dyes increased alteration in color and ultrastructure of hair., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The five-subunit WASH complex generates actin networks that participate in endocytic trafficking, migration and invasion in various cell types. Loss of one of the two subunits WASH or strumpellin in mice is lethal, but little is known about their role in mammals in vivo. We explored the role of strumpellin, which has previously been linked to hereditary spastic paraplegia, in the mouse melanocytic lineage. Strumpellin knockout in melanocytes revealed abnormal endocytic vesicle morphology but no impairment of migration in vitro or in vivo and no change in coat colour. Unexpectedly, WASH and filamentous actin could still localize to vesicles in the absence of strumpellin, although the shape and size of vesicles was altered. Blue native PAGE revealed the presence of two distinct WASH complexes, even in strumpellin knockout cells, revealing that the WASH complex can assemble and localize to endocytic compartments in cells in the absence of strumpellin., (© 2016 The Authors. Pigment Cell & Melanoma Research Published by John Wiley & Sons Ltd.)

The aim of the study was to analyze the effects of the first mating date, age and color variety on the conception rates in farm mink. We analyzed female mink reproductive performance in 492 Sapphire and 463 Standard Black females over 3 or 4 years. The analysis included the number of inefficient matings, the interval between the first inefficient mating and the efficient mating (copulation) and the conception rates. The results show a significant effect of female's age and color variety on the conception rates. The youngest, yearling females of either color needed a higher number of matings per conception, as compared to older, 2- and 3-year-old females. Black females demonstrated a higher number of inefficient matings (1.066), as compared with Sapphires (0.730). Yearling females were most often mated from 1 to 10 March, and older females from 11 to 20 March. Older females achieved better conception rates than the yearlings. Dates between 11 and 25 March proved to be the optimum for the first mating, since the highest conception rates were observed if the females had mated during this period., (© 2015 Japanese Society of Animal Science.)

Objectives: This study aims to evaluate the use of quantitative methods of measuring variation in scalp hair fiber shape and pigmentation and carry out exploratory data analysis on a limited sample of individuals from diverse populations in order to inform future avenues of research for the evolution of modern human hair variation., Methods: Cross-sectional area and shape and average curvature of scalp hair fibers were quantified using ImageJ. Pigmentation was analyzed using chemical methods estimating total melanin content through spectrophotometric methods, and eumelanin and pheomelanin content through HLPC analysis of melanin-specific degradation products., Results: The initial results reinforced findings from earlier, traditional studies. African and African Diaspora scalp hair was significantly curled, (East) Asian hair was significantly thick, and European hair was significantly lighter in color. However, pigmentation analyses revealed a high level of variability in the melanin content of non-European populations and analysis of curvature found a large range of variation in the average curvature of East African individuals., Conclusions: Overall, these results suggest the usefulness of chemical methods for the elucidation of nonperceptible differences in scalp hair color and highlight the need for improvements in our assessment and understanding of hair fiber curvature. Am J Phys Anthropol 160:341-352, 2016. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

The aim of this study was to examine associations of SES and ethnicity with hair cortisol and cortisone and to identify potential child and family characteristics that can assist in choosing covariates and potential confounders for analyses involving hair cortisol and cortisone concentrations. Hair samples were collected in 2484 6-year-old children from the Generation R Study, a prospective cohort in Rotterdam, the Netherlands. Measurements for cortisol and cortisone were used as the outcome in regression analyses. Predictors were SES, ethnicity, hair color and child characteristics such as birthweight, gestational age at birth, BMI, disease, allergy, and medication use. Lower family income, more children to be supported by this income, higher BMI and darker hair color were associated with higher hair cortisol and cortisone levels. Boys also showed higher levels. Ethnicity (Dutch and North European descent) was related to lower levels. High amounts of sun in the month of hair collection was related to higher levels of cortisone only. More recent hair washing was related to lower levels of cortisol and cortisone. Gestational age at birth, birth weight, age, medication use, hair washing frequency, educational level of the mother, marital status of the mother, disease and allergy were not associated with cortisol or cortisone levels. Our results serve as a starting point for choosing covariates and confounders in studies of substantive predictors or outcomes. Gender, BMI, income, the number of persons in a household, ethnicity, hair color and recency of hair washing are strongly suggested to take into account., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: Premature canities is a common yet incompletely understood dermatological entity with scarce demographic and clinical data., Aim: Evaluation of the demographic and clinical profile of cases with premature canities and to look for systemic associations., Methods: Fifty two self-reported cases of premature canities (onset before 20 years of age) and an equal number of healthy controls were recruited from the outpatient department of the Department of Dermatology, Guru Teg Bahadur Hospital Delhi, India from November 2011 to March 2013. A detailed history including onset, duration and pattern of involvement, a family history with pedigree charting and scalp examination were recorded on a predesigned proforma. A history of atopy was looked for in all study subjects and they were screened for thyroid disorder and diabetes., Results: The mean age of cases and controls was comparable. The mean age of onset of graying was 11.6 ± 3.6 years. The mean duration at the time of presentation was 39.8 ± 37.2 months. The frontal region was the earliest affected area in 25 (48.1%) cases. Positive family history of premature canities was reported in 39 (75%) cases with an equal prevalence on paternal and maternal sides. More than half of the cases, 29 (55.8%) reported having a first degree relative affected by premature canities, 13 (25%) had a second degree and 20 (38.5%) had a third degree relative affected. Atopy was found to be strongly associated with premature canities with an odds ratio of 3.8. No association with thyroid abnormality or diabetes mellitus was seen., Limitation: The study suffered from the limitation of a small sample size., Conclusion: It was observed that the process of graying mostly starts in the frontal region. It was also found to be associated with a strong family history and atopic predisposition. Larger studies are recommended to arrive at a definite conclusion.

Introduction: To investigate whether the membrane-associated transporter protein SLC45A2 is differentially expressed in the skin of sheep with different coat colors and to determine its correlation with coat color establishment in sheep., Material and Methods: The expression of SLC45A2 in sheep skin samples with different coat colors was qualitatively and quantitatively analyzed by PCR amplification, RT-PCR, immunohistochemical staining and Western blotting., Results: A 193-bp SLC45A2 CDS sequence was successfully amplified from sheep skin samples with diverse coat colors. RT-PCR analysis revealed that SLC45A2 mRNA was expressed in all sheep skin samples tested, with relative expression levels of 512.74 ± 121.51 in black skin, 143.38 ± 119.31 and 1.36 ± 0.09 in black dots and white dots of piebald skin, respectively, and 1.02 ± 0.23 in white skin (p < 0.01**). Positive SLC45A2 protein bands were also detected in all skin samples by Western blot analysis, with relative expression levels of 0.85 ± ± 0.17** in black skin, 0.60 ± 0.05** and 0.34 ± 0.07 in black dots and white dots of piebald skin, respectively, and 0.20 ± 0.05 in white skin (p < 0.01**). Immunohistochemical assays revealed that SLC45A2 was expressed in the hair follicle matrix, the inner and outer root sheath, and the dermal papilla in the skin tissues with different coat colors. These patterns were quantified by optical density (OD) analysis, which yielded relative expression levels of 0.23 ± 0.11 in black skin, 0.19 ± 0.09 and 0.10 ± 0.03 in black dots and white dots of piebald skin, respectively, and 0.08 ± 0.01 in white skin (p < 0.05*)., Conclusion: SLC45A2 is detectably expressed in sheep skin of all coat colors, though at significantly different levels. SLC45A2 may participate in the establishment of coat color by regulating the synthesis and trafficking of melanin.

Background: Junctional (flat) naevi predominate on the extremities, whereas dermal (raised) naevi are found primarily on the head, neck and trunk. Few studies have investigated the anatomical site prevalence of melanocytic naevi categorized using dermoscopy., Objectives: To identify the prevalence of dermoscopic patterns and structures of naevi from the back and legs of adolescents., Methods: Dermoscopic images of acquired melanocytic naevi were obtained from the back and legs of students from a population-based cohort in Framingham, Massachusetts. Naevi were classified into reticular, globular, homogeneous or complex dermoscopic patterns. Multinomial logistic regression modelling assessed the associations between dermoscopic pattern and anatomical location., Results: In total 509 participants (mean age 14 years) contributed 2320 back naevi and 637 leg naevi. Compared with homogeneous naevi, globular and complex naevi were more commonly observed on the back than the legs [odds ratio (OR) 29·39, 95% confidence interval (CI) 9·53-90·65, P < 0·001 and OR 6·8, 95% CI 2·7-17·14, P < 0·001, respectively], whereas reticular lesions were less likely to be observed on the back than on the legs (OR 0·67, 95% CI 0·54-0·84, P = 0·001). Naevi containing any globules were more prevalent on the back than on the legs (25% vs. 3·6%, P < 0·001). Naevi containing any network were more prevalent on the legs than on the back (56% vs. 40·6%, P < 0·001)., Conclusions: These findings add to a robust body of literature suggesting that dermoscopically defined globular and reticular naevi represent biologically distinct naevus subsets that differ in histopathological growth pattern, age- and anatomical-site-related prevalence, molecular phenotype and aetiological pathways., (© 2015 British Association of Dermatologists.)

Background: Awareness of individual risk may encourage improved prevention and early detection of melanoma., Methods: We evaluated the accuracy of self-reported pigmentation and nevus phenotype compared with clinical assessment, and examined agreement between nevus counts from selected anatomical regions. The sample included 456 cases with invasive cutaneous melanoma diagnosed between ages 18 to 39 years and 538 controls from the population-based Australian Melanoma Family Study. Participants completed a questionnaire about their pigmentation and nevus phenotype, and attended a dermatologic skin examination., Results: There was strong agreement between self-reported and clinical assessment of eye color [κ, = 0.78; 95% confidence interval (CI), 0.74-0.81]; and moderate agreement for hair color (κ = 0.46; 95% CI, 0.42-0.50). Agreement between self-reported skin color and spectrophotometer-derived measurements was poor (κ = 0.12; 95% CI, 0.08-0.16) to moderate (Spearman correlation rs = -0.37; 95% CI, -0.32 to -0.42). Participants tended to underestimate their nevus counts and pigmentation; men were more likely to underreport their skin color. The rs was 0.43 (95% CI, 0.38-0.49) comparing clinical total body nevus counts with self-reported nevus categories. There was good agreement between total body nevus counts and site-specific nevus counts, particularly on both arms., Conclusions: Young adults have suboptimal accuracy when assessing important risk characteristics including nevus numbers and pigmentation. Measuring nevus count on the arms is a good predictor of full body nevus count., Impact: These results have implications for the likely success of targeted public health programs that rely on self-assessment of these factors., (©2015 American Association for Cancer Research.)

Background: Premature graying of hair as a risk marker among young smokers has a potential of identifying coronary artery disease (CAD) at a very early stage. There is absence of literature that assesses premature graying of hair as an independent marker of CAD in smokers., Material and Methods: The present single-centre case control study enrolled a total of 62 consecutive chronic smokers (≤ 45 years) (Group I) and 60 consecutive young CAD patients (≤45 years) who were chronic smokers (Group II). Another group comprising of 114 patients (≤45 years) having no smoking history and no cardiac ailments either (Group III) was enrolled as control population. All subjects were males. A detailed history and clinical examination regarding conventional coronary risk factors and carotid intima media thickness was done in both groups., Results: The carotid intima media thickness, dyslipidemia and blood pressure were significantly higher in group I and II as compared to group III. When the groups were compared for graying of hair, it was found that the group II (i.e., smokers and CAD) had maximum prevalence of graying which was significantly higher than the control as well as smoker groups. The presence of premature graying of hair was associated with 3.24 times the risk of CAD on multiple logistic regression analysis., Conclusion: The presence of premature graying of hair was associated with an increased risk of CAD in young smokers. Premature graying of hair can be used as preliminary evidence by clinicians for classifying patients at risk for premature CAD especially in smokers.

The molecular mechanisms underlying the formation of coat colors in animals are poorly understood. Recent studies have demonstrated that microRNA play important roles in the control of melanogenesis and coat color in mammals. In a previous study, we characterized the miRNA expression profiles in alpaca skin with brown and white coat color and identified a novel miRNA (named lpa-miR-nov-66) that is expressed significantly higher in white skin compared to brown skin. The present study was conducted to determine the functional roles of this novel miRNA in the regulation of melanogenesis in alpaca melanocytes. lpa-miR-nov-66 is predicted to target the soluble guanylate cyclase (sGC) gene based on presence of a binding site in the sGC coding sequence (CDS). Overexpression of lpa-miR-nov-66 in alpaca melanocyes upregulated the expression of sGC both at the mRNA and protein level. Overexpression of lpa-miR-nov-66 in melanocyes also resulted in decreased expression of key melanogenic genes including tyrosinase (TYR), tyrosinase related protein 1 (TYRP1), and microphthalmia transcription factor (MITF). Our ELISA assays showed increased cyclic guanosine monophosphate (cGMP) but decreased cyclic adenosine monophosphate (cAMP) production in melanocytes overexpressing lpa-miR-nov-66. In addition, overexpression of lpa-miR-nov-66 also reduced melanin production in cultured melanocytes. Results support a role of lpa-miR-nov-66 in melanocytes by directly or indirectly targeting , which regulates melanogenesis via the cAMP pathway.

Background: As the 10-year mortality for localized cutaneous melanoma more than 1.00 mm thick approaches 40% following complete resection, non-therapeutic interventions that can supplement recommended active surveillance are needed. Although guidelines recommending nutrition, physical activity and tobacco cessation for cancer survivors have been published, data describing their associations with melanoma survivorship are lacking., Methods: Analysis of modifiable lifestyle behaviors collected on the 249 cases with melanomas more than 1.00 mm thick enrolled in the Connecticut Case-Control Study of Skin Self-Examination study was conducted. Independent associations with melanoma-specific survival were evaluated through Cox proportional hazards modeling adjusting for age, gender, Breslow thickness, ulceration and the presence of microsatellites. Independently significant variables were then combined into a single model and backwards elimination was employed until all remaining variables were significant at p<0.05., Results: Following adjustment for age, Breslow thickness and anatomic site of the index melanoma, daily fruit consumption was associated with improved melanoma-specific survival (HR=0.54; 95% CI: 0.34-0.86) whereas at least weekly red meat consumption was associated with worse outcomes (HR=1.84; 95% CI: 1.02-3.30). Natural red (HR=0.44; 95% CI: 0.22-0.88) or blond (HR=0.52; 95% CI: 0.29-0.94) hair were also favorably prognostic. Higher fish consumption was of borderline significance for improved survival only when considered independently (HR=0.65; 95% CI: 0.40-1.05); no association was seen following adjustment for red meat and fruit consumption (p>0.10)., Conclusions: Dietary choices at the time of diagnosis are associated with melanoma-specific survival in patients with melanomas more than 1.00 mm thick. Further validation of our findings in larger cohorts with repeated post-diagnostic measures is warranted to further evaluate whether dietary modification during the survivorship period can improve melanoma-specific survival., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Epidermal melanocyte precursors migrate into developing hair follicles to form the melanocyte stem cell system required to supply pigmented melanocytes necessary for hair pigmentation in repetitive hair cycles. Hair graying is caused by irreversible defects in the self-renewal and/or development of follicular melanocyte stem cells in the hair follicles. To investigate the mechanism(s) of hair graying during the normal aging process, we established a hair graying model in mice by repeatedly plucking or shaving trunk hairs. We repeatedly plucked or shaved trunk hairs to induce and accelerate the hair graying and counted the gray hairs. By using this functional model of hair graying in mice, we assessed the effects of genes known to affect melanocyte development, such as Kitl, hepatocyte growth factor (HGF) and endotheline 3 (ET3). After increasing the total numbers of cumulative hair cycles by plucking or shaving, we observed a significant increase in the gray hair of C57BL/6 mice. Kitl expression in the skin was the most effective for preventing hair graying and a significant effect was also confirmed for HGF and ET3 expression. The repeated hair plucking or shaving led to hair graying without any genetic lesion. Kitl is a more effective factor for prevention of hair graying than HGF or ET3. Our simple model of hair graying may provide a basic tool for screening the molecules or reagents preventing the progression of hair graying., (© 2014 Japanese Dermatological Association.)

The dermal papilla (DP) of the hair follicle is both a chemical and physical niche for epithelial progenitor cells that regenerate the cycling portion of the hair follicle and generate the hair shaft. Here, we review experiments that revealed the importance of the DP in regulating the characteristics of the hair shaft and frequency of hair follicle regeneration. More recent work showed that the size of this niche is dynamic and actively regulated and reduction in DP cell number per follicle is sufficient to cause hair thinning and loss. The formation of the DP during follicle neogenesis provides a context to contemplate the mechanisms that maintain DP size and the potential to exploit these processes for hair preservation or restoration., (Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.)

Background: The aim of this study was to determine whether eyebrow and eyelash whitening is an effective parameter in age estimation., Material and Methods: We evaluated 1545 patients. Age groups were 1-10, 11-20, 21-30, 31-40, 41-50, 51-60, 61-70, 71-80, and 81-90 years. Level of whitening was categorized as level 0: no whitening, level 1: 1-3 strands, level 2: 3-10 strands, level 3: 10 strands-2/3 whitening, level 4: >3/4 whitening., Results: Mean age was 42.39 ± 20.01. While there was no eyebrow whitening in 87% of the subjects, level 4 whitening of eyebrows was observed in 0,8% of the subjects. There was no eyelash whitening in 97,7% of the subjects and no level 4 eyelash whitening was detected in any subject. Men had significantly more level 1, 2, 3, and 4 eyebrow whitening compared with women. There was no gender difference in terms of eyelash whitening level. There was no eyebrow and eyelash whitening in subjects age 1-40 years; whitening began in the 41-50 years age group and increased with age in other groups. Mean age was 39.59 ± 19.63 years in subjects with no eyebrow whitening; 59 years in level 1, 61 years in level 2, 63 years in level 3, and 69 years in level 4 eyebrow whitening. Mean age was 41.85 ± 19.87 in subjects with no eyelash whitening; and 63.57 ± 10.75 in those with whitening., Conclusions: Particularly after 41-50 years of age, level of eyebrow and eyelash whitening may be among a useful age estimation parameter.

An obvious sign of ageing is hair greying, or the loss of pigment production and deposition within the hair shafts. Numerous mechanisms, acting at different levels and follicular locations, contribute to hair greying, ranging from melanocyte stem cells defects to follicular melanocyte death. One key issue that is in common to these processes is oxidative damage. At the hair follicle stem cells niche, oxidative stress, accelerated by B-cell lymphoma 2 gene (BCL-2) depletion, leads to selective apoptosis and diminution of melanocyte stem cells, reducing the repopulation of newly formed anagen follicles. Melanotic bulbar melanocytes express high levels of BCL-2 to enable survival from melanogenesis- and ultraviolet A (UVA)-induced reactive oxygen species (ROS) attacks. With ageing, the bulbar melanocyte expression of anti-oxidant proteins such as BCL-2, and possibly TRP-2, is reduced, and the dedicated enzymatic anti-oxidant defence system throughout the follicle weakens, resulting in enhanced oxidative stress. A marked reduction in catalase expression and activity results in millimolar accumulation of hydrogen peroxide, contributing to bulbar melanocyte malfunction and death. Interestingly, amelanotic melanocytes at the outer root sheath (ORS) are somewhat less affected by these processes and survive for longer time even within the white, ageing hair follicles. Better understanding of the overtime susceptibility of melanocytes to oxidative stress at the different follicular locations might yield clues to possible therapies for the prevention and reversal of hair greying., (© 2013 Society of Cosmetic Scientists and the Société Française de Cosmétologie.)

Although, of no vital value, hair plays a significant role in expressing any person's psychosocial status. Many cosmetic and styling methods are available for hair. This study aimed to examine the microscopic changes in women with hair coloring, hair waving, or hair ironing in comparison with normal controls. In a cross-sectional study, 154 Iranian women were recruited and categorized in 4 groups: controls (n = 35) who had not dyed, waved or ironed their hair within the last 6 months; dyed-hair group (n = 49) who had dyed their hair using standard chemical hair colors at least three times within the last 6 months; waved-hair group (n = 35) who had frizzled their hair within the last 6 months and ironed-hair group (n = 35) who had ironed their hair at least 3 times a weak using a temperature more than 30 degrees C within the last 6 months. Hair samples of all four groups were examined microscopically, and the results were compared with the controls. The rate of abnormal findings was 17.1% in the controls, 53.1% in the dyed-hair group, 45.7% in the waved-hair group, and 54.3% in the ironed-hair group. Abnormal findings were significantly more frequent in the last three groups comparing with the controls (p < 0.05). Trichorrhexis was 17.1, 34.7, 40 and 11.4%; kinking was 0, 2, 2.9 and 25.7%; pseudo pili-annulati was 0, 6.1, 0 and 17.1%; trichonodosis was 0, 6.1, 0 and 0%; tracheoschises was 0, 2, 2.9 and 0% and trichoptilosis was 0, 2, 0 and 0% in the mentioned groups, respectively. Based on the results of the present study, hair coloring, waving and ironing all can induce abnormalities in the hair in comparison with the hairs of nonusers.

Coat color and pattern variations in domestic animals are frequently inherited as simple monogenic traits, but a number are known to have a complex genetic basis. While the analysis of complex trait data remains a challenge in all species, we can use the reduced haplotypic diversity in domestic animal populations to gain insight into the genomic interactions underlying complex phenotypes. White face and leg markings are examples of complex traits in horses where little is known of the underlying genetics. In this study, Franches-Montagnes (FM) horses were scored for the occurrence of white facial and leg markings using a standardized scoring system. A genome-wide association study (GWAS) was performed for several white patterning traits in 1,077 FM horses. Seven quantitative trait loci (QTL) affecting the white marking score with p-values p≤10(-4) were identified. Three loci, MC1R and the known white spotting genes, KIT and MITF, were identified as the major loci underlying the extent of white patterning in this breed. Together, the seven loci explain 54% of the genetic variance in total white marking score, while MITF and KIT alone account for 26%. Although MITF and KIT are the major loci controlling white patterning, their influence varies according to the basic coat color of the horse and the specific body location of the white patterning. Fine mapping across the MITF and KIT loci was used to characterize haplotypes present. Phylogenetic relationships among haplotypes were calculated to assess their selective and evolutionary influences on the extent of white patterning. This novel approach shows that KIT and MITF act in an additive manner and that accumulating mutations at these loci progressively increase the extent of white markings.