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Genomic organization and sequence of D12S53E (Pmel 17), the human homologue of the mouse silver (si) locus.

We have determined the DNA sequence and genomic organization of D12S53E (Pmel 17), the human homologue of the mouse silver (si) locus. D12S53E encodes a melanosomal matrix protein whose expression is closely correlated with cellular melanin content and which is a frequent melanoma tumor antigen recognized by cytotoxic T lymphocytes. D12S53E is a likely candidate gene for some cases of human oculocutaneous albinism not associated with known albinism loci.

Alternative Splicing↗

Associated factors in the prevalence of more than 50 common melanocytic nevi, atypical melanocytic nevi, and actinic lentigines: multicenter case-control study of the Central Malignant Melanoma Registry of the German Dermatological Society.

Several case-control studies identified common and atypical melanocytic nevi as major risk indicators for the development of cutaneous melanoma. The present investigation was planned to detect factors associated with the prevalence of these melanoma risk markers. Whole-body examination findings and interview data of 513 melanoma patients and 498 age- and sex-matched control subjects were analyzed. Existence of more than 50 common melanocytic nevi and the presence of atypical melanocytic nevi were significantly related to age and gender, with significantly elevated relative risk for their prevalence before the age of 60 and in males. Additionally, sunburns before the age of 20 were significantly associated with both more than 50 common melanocytic nevi (relative risk = 1.7) and the presence of atypical melanocytic nevi (relative risk = 1.5). Actinic lentigines were found more frequently with increasing age, and the presence of actinic lentigines was significantly related to a tendency of freckling in adolescence (relative risk = 2.0) and to two or more sunburns after the age of 20 (relative risk = 1.6). In conclusion, sunburns before the age of 20 contribute to the development of multiple melanocytic nevi and atypical melanocytic nevi. In adulthood, this type of sun exposure is associated with the development of actinic lentigines. The relative risk of developing cutaneous melanoma increases in association with the development of these benign melanocytic lesions.

Adolescent↗

Trichochromes in the urine of melanoma patients.

The urine of patients with melanoma metastases and increased urinary excretion of 5-S-cysteinyldopa was examined for trichochromes. Five of 16 patients showed urinary excretion of trichochromes B and C. None excreted trichochromes E or F. All patients showing trichochrome excretion had very large amounts of cysteinyldopa in their urine.

Adult↗

The time course of photoadaptation and pigmentation studied using a novel method to distinguish pigmentation from erythema.

The dynamics of human pigmentation in response to ultraviolet radiation (UVR) remain poorly characterized. In part, this is attributable to methodological issues relating to the overlap in spectra of hemoglobin and melanin. We describe a new method, based on the recording of reflectance properties following iontophoresis of a potent vasoconstrictor, noradrenaline. This removes the influence of blood, allowing measurement of pigmentation, represented as L* on the L*a*b* scale. Blood flow was separately assessed using laser Doppler flowmetry. We show that there is a clear dose response with the dose of UVR administered, that pigmentation peaks at 1 wk and declines over the following 10 wk, but does not return to baseline within this period. We show clear differences in the degree, but not the temporal pattern of pigmentation between different pigmentary groups. We also report that the relation between facultative pigment and constitutive pigment is incomplete, with a wide scatter of responses for the development of pigmentation irrespective of constitutive levels. For comparison we also document overall photoadaptation and relate changes in pigmentation to the overall changes in photoadaptation.

Adaptation, Physiological↗

Returning to the same area of hair surfaces before and after treatment: a longitudinal AFM technique.

We report the use of longitudinal (aspect ratio > 1 : 1) scanning atomic force microscopy as an aid in returning to the same area of hair fibres after bleaching, treatment with a commercial shampoo or the application of a 'leave-on' conditioner product. The bleaching treatment used in this study was not found to affect the cuticular architecture and lateral force microscopy (LFM) also showed little difference after treatment, reflecting the homogeneity of the newly revealed surfaces. After treatment with a commercial shampoo, the hair sample again showed very little difference in topography or lateral force characteristics. Hair treated with the leave-on conditioner product also showed no major topographical changes. LFM traces, however, showed regions between the ghost edge, marking the original position of the scale edge before cuticular erosion, and the existing scale edge, to have higher frictional properties than distal regions of the cuticle. A thin film of the leave-on product thus seems to form in this region and extends from the foot of the scale edge.

Europe↗

Prevalence of male and female pattern hair loss in Maryborough.

Maryborough, in central Victoria has an approximate population of 8000 and census data is well matched for Australia overall. Australia has compulsory voting and registration on the electoral roll. To determine the age-related prevalence of balding among men and women in Maryborough we conducted a postal survey of 5000 men and women aged 20 or older, and 427 were invited to attend for examination. Additional data was collected on dandruff, presence of gray hair. Supplementary questionnaires were sent to 340 children aged 5-9, attending a coeducational primary school. 1456 adults (34.1%) responded to the questionnaire. 396 attended for examination. The prevalence of androgenetic alopecia (AGA) increased with advancing age. 98.6% of men had bitemporal recession and severity was significantly associated with vertex and mid-frontal hair loss (p <0.01) but not age (p = 0.06). In all, 64.4% of women had bitemporal hair loss, and similar to men there was a significant association with mid-frontal hair loss (p =0.042) but not age (p =0.467). One hundred and forty children with completed questionnaires were examined. All 72 females and 68 males were assessed as stage 1 on the mid-line part and with no bitemporal recession (frequency stage 1 = 100%, 95% CI (confidence interval) 97.4%-100%). A significant but weak positive association existed between presence of gray hair and history of dandruff (p<0.01). The prevalence of mid-frontal hair loss increases with age and affects 57% of women and 73.5% of men aged 80 and over.

Adult↗

Genetic control of PI and GC variants in the American mink.

Genetic polymorphism of the serum alpha-protease inhibitor (PI) and group-specific component (GC) in minks was revealed using one-dimensional polyacrylamide gel electrophoresis and immunoblotting. Two codominant alleles were identified at each of the two loci. The data ruled out the possibility of any linkage between the PI, GC and the coat colour gene Crystal (Cr).

Animals↗

Localizing the X-linked orange colour phenotype using feline resource families.

Many genes influencing mammalian coat colours are well conserved. While genes responsible for pelage phenotypes in one species provide strong evidence for a candidate gene in a different species, the X-linked orange phenotype of the domestic cat is unique within mammals. The orange locus (O) undergoes X-inactivation, producing females that express both wildtype black (wt) and orange (variant) phenotypes when heterozygous (tortoiseshell). The orange locus has not yet been localized on the X chromosome. Tortoiseshell male cats have been identified but have been shown to be sex chromosome trisomies (XXY). To localize the cat orange locus, 10 feline-derived X-linked microsatellites were analysed in two extended cat pedigrees consisting of 79 and 55 individuals, respectively, segregating for the orange phenotype. Linkage analyses excluded close association of orange in the vicinity of the nine informative X-linked microsatellites. One marker was not polymorphic within either family. Several markers suggested exclusion (Z < -2.0) at distances of 7.5-33 cM. Exclusion analyses suggested a possible location for orange a 14 cM region near Xcen. Recombination distances of markers in the segregating feline pedigrees were reduced as compared with the feline interspecies backcross family. Thus, the presented pedigrees may be useful as reference families for the domestic cat because more accurate recombination rates for domestic cats can be determined.

Animals↗

Polymorphism at the porcine Dominant white/KIT locus influence coat colour and peripheral blood cell measures.

We have examined the phenotype of different KIT genotypes with regard to coat colour and several blood parameters (erythrocyte numbers and measures, total and differential leucocyte numbers, haematocrit and haemoglobin levels and serum components). The effect of two different iron supplement regimes (one or two iron injections) on the blood parameters was also examined. For a total of 184 cross-bred piglets (different combinations of Hampshire, Landrace and Yorkshire) blood parameters were measured four times during their first month of life, and the KIT genotypes of these and 70 additional cross-bred piglets were determined. Eight different KIT genotypes were identified, which confirms the large allelic diversity at the KIT locus in commercial pig populations. The results showed that pigs with different KIT genotypes differ both in coat colour and in haematological parameters. In general, homozygous Dominant white (I/I) piglets had larger erythrocytes with lower haemoglobin concentration, indicating a mild macrocytic anaemia. The effect of two compared with one iron injection was also most pronounced for the I/I piglets.

Animals↗

White spotting in the domestic cat (Felis catus) maps near KIT on feline chromosome B1.

Five feline-derived microsatellite markers were genotyped in a large pedigree of cats that segregates for ventral white spotting. Both KIT and EDNRB cause similar white spotting phenotypes in other species. Thus, three of the five microsatellite markers chosen were on feline chromosome B1 in close proximity to KIT; the other two markers were on feline chromosome A1 near EDNRB. Pairwise linkage analysis supported linkage of the white spotting with the three chromosome B1 markers but not with the two chromosome A1 markers. This study indicates that KIT, or another gene within the linked region, is a candidate for white spotting in cats. Platelet-derived growth factor alpha (PDGFRA) is also a strong candidate, assuming that the KIT-PDGFRA linkage group, which is conserved in many mammalian species, is also conserved in the cat.

Animals↗

Mutations in the melanocortin 1 receptor (MC1R) gene are associated with coat colours in the domestic rabbit (Oryctolagus cuniculus).

We sequenced almost the complete coding region of the MC1R gene in several domestic rabbits (Oryctolagus cuniculus) and identified four alleles: two wild-type alleles differing by two synonymous single nucleotide polymorphisms (c.333A>G;c.555T>C), one allele with a 30-nucleotide in-frame deletion (c.304_333del30) and one allele with a 6-nucleotide in-frame deletion (c.280_285del6). A polymerase chain reaction-based protocol was used to distinguish the wild-type alleles from the other two alleles in 263 rabbits belonging to 37 breeds or strains. All red/fawn/yellow rabbits were homozygous for the c.304_333del30 allele. This allele represents the recessive e allele at the extension locus identified through pioneering genetic studies in this species. All Californian, Checkered, Giant White and New Zealand White rabbits were homozygous for allele c.280_285del6, which was also observed in the heterozygous condition in a few other breeds. Black coat colour is part of the standard colour in Californian and Checkered breeds, in contrast to the two albino breeds, Giant White and New Zealand White. Following the nomenclature established for the rabbit extension locus, the c.280_285del6 allele, which is dominant over c.304_333del30, may be allele E(D) or allele E(S).

Alleles↗