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Inheritance of dilute coat color with pink eye in the Japanese field vole (Microtus montebelli) was investigated by mating of the dilute mutant with a normal agouti vole and a white vole. As the results, it was cleared that an autosomal recessive gene p is responsible for the pink-eyed dilution in M. montebelli.
We conducted a case-control interview study among 1277 subjects (407 patients, 870 controls selected by using random digit dial) in 11 western United States to determine whether uveal melanoma and cutaneous melanoma shared common risk factors. After adjustment for other factors, the risk of uveal melanoma was increased for those with green, gray, or hazel eyes [relative risk (RR) = 2.5, P less than 0.001] or blue eyes (RR = 2.2, P less than 0.001) when compared to brown. A tendency to sunburn after 0.5 h midday summer sun exposure increased risk for uveal melanoma (burn with tanning RR = 1.5, P = 0.02; burn with little tanning RR = 1.8, P less than 0.001; burn with no tanning RR = 1.7, P = 0.002); as did exposure to UV or black lights (RR = 3.7, P = 0.003); and welding burn, sunburn of the eye, or snow blindness (RR = 7.2, P less than 0.001). An association with uveal melanoma was also noted with an increasing number of large nevi (P = 0.04 for trend), although the individual risk estimates were not remarkable. These data suggest that host factors and exposure to UV light are risk factors for uveal melanoma.
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Different clinico-pathologic subtypes and anatomic sites of basal-cell carcinoma (BCC) may display distinct characteristics and mechanisms of development. However, scanty information exists on potential differences in etiological factors for BCC according to histotype and anatomic location. Thus, we analyzed data from an Italian case-control study, including 528 subjects with newly diagnosed, histologically confirmed BCC and 512 controls admitted to the same hospitals with acute conditions. The multivariate odds ratio (OR) of nodular (OR=1.53) but not superficial (OR=0.71) BCC was increased for occupational exposure to sunlight. Considering the anatomic site of BCC, the corresponding values were 1.46 for head/neck and 0.74 for truncal location. Direct associations were observed with recreational sunlight exposure, eye color, red hair, and number and early age of severe sunburn episodes, along with some differences in risk between histotypes and anatomic sites. This study confirmed the role of (intermittent) sun exposure and phenotypic characteristics as risk factors for BCC, and suggested etiological differences between nodular and superficial histotypes and between head/neck and truncal locations.
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Six-hundred and fifteen young healthy Italian males were examined for the number, localization and clinical features of melanocytic naevi. The data were correlated with the phenotype and skin type of the subjects. Eighty-eight per cent had melanocytic naevi, 7% congenital naevi and 21.3% atypical naevi with a diameter greater than 5 mm and indistinct or irregular borders and were variable in colour. Of the sample only 2.43% had more than 30 naevi. Those subjects with blond or red hair, fair skin, blue or green eyes and with a skin type of I and II had higher numbers of naevi which were more often atypical than those subjects with dark hair, brown eyes and who were skin types III-V.
The classical mouse fancy Agouti gene is responsible for the wild-type coat color where hairs are banded black and yellow. The Agouti gene encodes a 131-amino-acid secreted protein product that regulates phaeomelanin synthesis by melanocytes in mice. Mice with a dominant mutation at this locus, Ay, develop a yellow coat color, obesity, and diabetes, as the result of a deletion that results in ectopic overexpression of the Agouti gene mRNA in all tissues examined. Obesity and diabetes in Ay mutant mice could be caused by circulation of the protein, or localized action in specific tissues as a paracrine factor acting in cell-cell communication. To test these two possibilities, the Agouti cDNA was overexpressed in the skin of transgenic mice using either the Tyrosinase-Related Protein-1 or the keratin-14 (K14) promoter, the latter with and without an intron. The K14 promoter directed high constitutive levels of expression of Agouti mRNA in the skin, and several lines of transgenic mice exhibited coat colors resembling dominant Agouti allele phenotypes. Two highly expressing K14-Agouti transgenic lines, with light-yellow pelage, were analyzed for obesity and hyperglycemia. The transgenic mice were not significantly different from the controls (P > 0.05), indicating that the Agouti product does not act as an endocrine factor. RNase protection assays revealed a correlation between the levels of dorsal and ventral skin expression with pigmentation/phaeomelanin phenotypes. Co-injection experiments with the Agouti transgenes and other transgenes demonstrated co-integration of the two constructs at the same chromosomal site in approximately 95% of F1 progeny, allowing transgene inheritance to be visibly detected.
Melanocortin 1 receptor (MC1R) gene variants are associated with red hair and fair skin color. We assessed the associations of common MC1R genotypes with the risks of 3 types of skin cancer simultaneously in a nested case-control study within the Nurses' Health Study (219 melanoma, 286 squamous cell carcinoma (SCC), and 300 basal cell carcinoma (BCC) cases, and 873 controls). We found that the 151Cys, 160Trp and 294His variants were significantly associated with red hair, fair skin color and childhood tanning tendency. The MC1R variants, especially the 151Cys variant, were associated with increased risks of the 3 types of skin cancer, after controlling for hair color, skin color and other skin cancer risk factors. Carriers of the 151Cys variant had an OR of 1.65 (95% CI, 1.04-2.59) for melanoma, 1.67 (1.12-2.49) for SCC and 1.56 (1.03-2.34) for BCC. Women with medium or olive skin color carrying 1 nonred hair color allele and 1 red hair color allele had the highest risk of melanoma. A similar interaction pattern was observed for red hair and carrying at least 1 red hair color allele on melanoma risk. We also observed that the 151Cys variant contributed additional melanoma risk among red-haired women. The information on MC1R status modestly improved the risk prediction; the increase was significant for melanoma and BCC (p, 0.004 and 0.05, respectively). These findings indicated that the effects of the MC1R variants on skin cancer risk were independent from self-reported phenotypic pigmentation.
The meaning of the coat colour of the dog reaches further than only to the field of breeding for beauty. Besides aspects of destination (hunting dogs, herding dogs) the clinical meaning is of particular interest. Some colours can show certain defects. Diseases of allowed colours are the colour dilution alopecia (CDA) in diluted (mostly "blue") pigmentation with its subtype of Black hair follicular dysplasia (BHFD) in black pigmentation and congenital deafness in extreme piebalds. Not allowed coat colours, which are connected with defects, are the extreme dapple of the Merle-syndrome and the "grey" Collie with cyclic hematopoesis.
Color mutations occur frequently among rodents. Here we describe a blond coat color mutation in the meadow vole (Microtus pennsylvanicus) that arose in a captive breeding colony established from wild-caught animals from southern Illinois. The blond coat coloration results from changes in the color and distribution of pigments in the hair. The mutation is monogenic autosomal recessive.
By amplifying the melanocortin type 1 receptor from the woolly mammoth, we can report the complete nucleotide sequence of a nuclear-encoded gene from an extinct species. We found two alleles and show that one allele produces a functional protein whereas the other one encodes a protein with strongly reduced activity. This finding suggests that mammoths may have been polymorphic in coat color, with both dark- and light-haired individuals co-occurring.
Hair testing for drugs of abuse is a developing technology that offers the possibility of longer detection times than is commonly obtained with urine or blood analysis. There are many uncertainties concerning how drugs enter hair and factors that affect drug deposition and residence in hair. Possible routes of drug entry include diffusion from blood, sweat, sebum, and skin and entry from the environment. Evidence is reviewed regarding the importance of each of these routes as possible contributors to drug deposition in hair. Binding to specific sites in hair may involve both electrostatic forces and weaker attractions, such as van der Waals forces. Melanin and protein constituents of hair may serve as binding sites. Recent in vitro studies suggest that the color of hair or melanin content may be the major determinant of cocaine binding and, consequently, may result in color or ethnic bias in hair testing.
Scalp hair growth and patterning are closely associated with the development of the central nervous system. A number of genetic, metabolic, and neurologic disorders are associated with recognizable scalp hair abnormalities. For this reason, a systematic step-by-step assessment of the hair and scalp should be an integral part of every initial newborn physical assessment. This article reviews the clinically relevant embryology related to fetal scalp hair formation. Normal cycles of hair growth and loss are discussed. A systematic review of typical newborn scalp hair characteristics such as color, quantity, texture, direction of growth, hairlines, and hair whorls is provided. Conditions associated with abnormal hair color, quality, quantity, and distribution are presented in a series of clinical photographs, and their salient features are discussed. Abnormal hair often occurs as a constellation of findings; implications for clinical care and further investigation will be briefly described.
Using individual subject data from 10 case-control studies, comprising over 3000 cases and almost 4000 controls, we have estimated the relative risk of melanoma associated with aspects of complexion, namely, hair, eye and skin colour and freckling in adulthood, and have examined the relationships between these factors and naevus count in terms of melanoma risk. Compared with individuals with black or dark brown hair, the relative risks for developing melanoma in those with light brown, blonde and red hair were 1.49 (95% CI 1.31, 1.70), 1.84 (95% CI 1.54, 2.21) and 2.38 (95% CI 1.90, 2.97), respectively. Individuals with blue eyes had a risk 1.55 (95% CI 1.35, 1.78) times that for those with brown eyes, or 1.15 (95% CI 0.94, 1.40) after adjusting for hair colour and freckling in adulthood. The relative risks associated with hair and eye colour were independent of those for naevus count and skin colour. Light skin colour and high freckle density were also highly significant risk factors, independent of each other and of naevus count and hair and eye colour. The risks associated with these factors, while individually modest, are largely independent, and thus pigmentation characteristics and freckling tendency should be useful in identifying high risk groups to be targeted for prevention.
We directly compared risk factors between 214 histologically confirmed melanomas (CMM), 215 basal-cell carcinomas (BCC) and 139 squamous-cell carcinomas (SCC) in a multiple case-case-control study with 349 controls from patients without dermatological disease admitted to the same hospitals. Subjects with fair hair had a significant risk increase for all types of tumours at a comparable level (OR(adj) for blonde hair: CMM 2.3; SCC 2.4; BCC 2.3). The effect of pale eyes was significant and similar for CMM and BCC (OR(adj) 2.6). Intermittent sun exposure measured in hours spent at beach during holidays was significant for both CMM (OR(adj) 2.6 for more than 7000 lifelong hours) and BCC (OR(adj) 2.1 for more than 7000 lifelong hours), while SCC exhibited a significant risk increase for chronic exposure to sunlight measured in hours of outdoor work (OR(adj) 2.2 for more than 6000 lifelong hours). In the case-case comparison using a multinomial logistic regression model, we found a statistically significant risk difference for pale eyes, and number of naevi in the CMM group, compared to other skin cancers. For intermittent sun exposure, there was a significant risk difference of BCC when compared to the risk of SCC. Factors influencing risk of SCC are different, with chronic exposure to sun playing a major role in causing this type of carcinoma.
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