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At least 181 records · Page 10Linked to original sources
PubMed1990

Low-pigment skin type and predisposition for development of type I diabetes.

To ascertain whether skin pigmentation type and sensitivity to ultraviolet (UV) light are associated with susceptibility to type I (insulin-dependent) diabetes, 55 type I diabetic patients were examined, 38 new-onset and 17 long-term cases. They were compared to 72 control subjects of the same geographic region and nationality. To evaluate the individual skin pigmentation type, a standardized questionnaire was developed. Reactivity to UV light was determined by a stepwise-graded UV irradiation. Significantly more diabetic patients in southern Germany had blue eyes than nondiabetic control subjects (55 vs. 26%, P less than 0.01), and significantly more diabetic patients had a low-pigment eye color (blue or green) than control subjects (66 vs. 38%, P less than 0.01). In addition, more fair skin color was noted among diabetic versus control subjects (84 vs. 60%, P less than 0.01). In response to UV irradiation, diabetic patients more often showed an increased UV-light sensitivity than control subjects (83 vs. 23%, P less than 0.001). The relative risk for susceptibility to type I diabetes in subjects with low-pigment eye color was 3.1, in subjects with fair skin type 3.4, and in subjects with increased UV-light sensitivity 5.8. The highest risk for the development of diabetes was seen in subjects who had low-pigment eye color and/or increased UV-light sensitivity (95 vs. 51%, P = 0.00002, odds ratio 17.4). We conclude that a low-pigment skin type may predispose for the development of type I diabetes.

Adult↗
PubMed2005

Single nucleotide polymorphisms in the MATP gene are associated with normal human pigmentation variation.

Human physical pigmentation is determined by the type and amount of melanin and the process of pigmentation production probably involves more than 100 genes. A failure to synthesize melanin results in oculocutaneous albinism (OCA). A recently identified form of OCA results from mutations in the Membrane Associated Transporter Protein (MATP) gene. The role of MATP in human pigmentation is not clear. We investigated the role of two nonpathogenic nonsynonymous single nucleotide polymorphisms (SNPs) in the MATP gene to determine if they are associated with normal human skin, hair, and eye color variation. A total of 608 individuals from four different population groups (456 Caucasians, 31 Asians, 70 African-Americans, and 51 Australian Aborigines) were genotyped for c.814G>A (p.Glu272Lys) and c.1122C>G (p.Phe374Leu). Results indicate that the allele frequencies of both polymorphisms are significantly different between population groups. The two alleles, 374Leu and 272Lys, are significantly associated with dark hair, skin, and eye color in Caucasians. The odds ratios (ORs) of the LeuLeu genotype for black hair and olive skin are 25.63 and 28.65, respectively, and for the LysLys genotype are 43.23 and 8.27, respectively. The OR for eye color is lower at 3.48 for the LeuLeu and 6.57 for LysLys genotypes. This is the first report of this highly significant association of MATP polymorphisms with normal human pigmentation variation.

Black or African American↗
PubMed2026

Phenotypic and genotypic risk factors for uveal melanoma in a high ambient UV radiation environment.

BACKGROUND: Most evidence regarding risk factors for uveal melanoma (UM) derives from case-control studies prone to recall bias, and its rarity has limited prospective research. To address these gaps, we applied a population-based case-control design incorporating polygenic risk scores and Mendelian randomization to explore genetic and phenotypic determinants of UM risk. METHODS: The study was conducted in Queensland, Australia. Incident UM cases diagnosed between 2011 and 2022 were recruited through specialist ocular oncology clinics. Controls were participants in the QSkin Sun and Health Study, a prospective cohort of 43,794 adults aged 40-69 at baseline (2010-2011). Demographic, phenotypic, and sun exposure factors were harmonized across studies. Polygenic risk scores were calculated for pigmentation traits and nevi characteristics using genome-wide association study datasets, and Mendelian randomization was used to assess potential causal relationships with UM risk. RESULTS: Among 485 UM cases and 43,724 controls, several phenotypic traits were strongly associated with UM risk: male sex, blue or light eye color, inability to tan, freckling, and high nevus density. A family history of cutaneous melanoma and a personal history of keratinocyte cancer were also associated with higher risk. Polygenic risk score analyses confirmed significant associations for eye color and freckling. Mendelian randomization analyses supported causal relationships between lighter eye color, freckling propensity, reduced tanning ability and UM risk. CONCLUSIONS: These findings provide genetic evidence supporting a causal role for pigmentation-related traits in UM susceptibility. IMPACT: This evidence may help refine risk assessment and inform counselling for individuals with suspicious ocular lesions.

Journal Article↗
PubMed1964

XANTHINE DEHYDROGENASE: DIFFERENCES IN ACTIVITY AMONG DROSOPHILA STRAINS.

In Drosophila melanogaster, mutants at two loci are known to lack detectable amounts of xanthine dehydrogenase activity. These are the maroon-like eye-color locus on the X chromosome and the rosy-eye-color locus on the third chromosome (52+/-). A survey was made of the xanthine dehydrogenase content of 98 wild-type strains of D. melanogaster. One strain with 25 percent of the xanthine dehydrogenase activity found in normal flies is described. Strains with high xanthine dehydrogenase activity have also been obtained by selection.

Animals↗
PubMed1976

Extension of the limits of the XDH structural element in Drosophila melanogaster.

Experiments expanding the array of mutants affecting the xanthine dehydrogenase (XDH) structural element in Drosophila melanogaster are described. These include rosy eye color mutants which exhibit interallelic complementation, and mutants with normal eye color but lowered levels of XDH. Evidence is presented which argues that these are structural alterations in the enzyme. Recombination experiments were performed using these mutants as well as some electrophoretic variants. The two ends of the rosy locus are marked with mutant sites which are clearly structural in nature; the XDH structural element and the rosy null mutant map are completely concordant. A possible procedure to recover control element mutants is described.

Animals↗
PubMed1977

A photometric study of the color of health gingiva.

An apparatus was developed that was found suitable for measuring gingival color in terms of reflectance at 6328 A. A total of 445 readings were taken on 95 Caucasian subjects in order to determine certain properties of healthy gingival color. It was determined that: 1. Healthy adult gingival color ranged in reflectance from 17% to 45% of the magnesium oxide standard, with a mean of 32%. 2. Gingival color of children was lighter than that of adults. The reflectance of children's gingiva ranged from 31% to 43%, with a mean of 35%. 3. Gingival color did not vary with the sex of the individual. 4. Gingival color was lighter in individuals with blonde hair than in individuals with brown hair. 5. Gingival color was darker in individuals with darker eye color. 6. Gingival color was lighter in individuals with geographic origins that are commonly related to lighter complexions. 7. Gingival color did not vary with age, within the adult range covered in this study. 8. Gingival color did not vary with the following physiological and physical factors: menstrual period, use of oral contraceptives, smoking habits, moistness or dryness of the gingiva, which side was measured, time of day, or time after toothbrushing, smoking a cigarette, eating an apple, or drinking a hot beverage.

Adult↗
PubMed2002

Enhancer of garnet/deltaAP-3 is a cryptic allele of the white gene and identifies the intracellular transport system for the white protein.

The white gene encodes an ABC-type transmembrane transporter that has a role in normal eye pigment deposition. In addition, overexpression in Drosophila leads to homosexual male courtship. Its human homologue has been implicated in cholesterol transport in macrophages and in mood disorders in human males. The garnet gene is a member of a group of other Drosophila eye colour genes that have been shown, or proposed, to function in intracellular protein transport. Recent molecular analysis indicates that it encodes the delta subunit of the AP-3 adaptin complex involved in vesicle transport from the trans-Golgi network to lysosomes and related organelles, such as pigment granules. This identification revealed a novel role for intracellular vesicular transport in Drosophila pigmentation. To further analyze this intracellular transport system, we examined the genetic interactions between garnet and a second site enhancer mutation, enhancer of garnet (e(g)). We show here that e(g) is a cryptic allele of the white gene. The white-garnet interaction is highly sensitive to the levels of both gene products but also shows some allele specificity for the white gene. The additive effect on pigmentation and the predicted protein products of these genes suggest that the garnet/AP-3 transport system ensures the correct intracellular localization of the white gene product. This model is further supported by the observation of homosexual male courtship behavior in garnet mutants, similar to that seen in flies overexpressing, and presumably mis-sorting, the white gene product. The w(e(g)) allele also enhances mutations in the subset of other eye-color genes with phenotypes similar to garnet. This observation supports a role for these genes in intracellular transport and leads to a model whereby incorrect sorting of the white gene product can explain the pigmentation phenotypes of an entire group of eye-color genes.

ATP-Binding Cassette Transporters↗
PubMed1989

Physical and physiological correlates of behavioral inhibition.

Previous investigations have suggested that the temperamental quality of inhibition is related to the threshold of reactivity to unfamiliar events within certain limbic structures. In earlier work, children in three independent samples who had been selected to be inhibited were more likely to have blue than brown eyes, whereas uninhibited children were more likely to have brown eyes. The present study, which selected two-year-old children on the basis of eye color (blue or brown) rather than behavior, found a significant association between blue eyes and behavioral inhibition, and between brown eyes and an uninhibited style. Although the inhibited children were more likely to have a high and stable heart rate than were the uninhibited children, there was no relation between eye color and these cardiac measures. Several interpretations of the association between these temperamental categories and iris pigmentation are proposed.

Arousal↗
PubMed1995

A genetic analysis of the Suppressor 2 of zeste complex of Drosophila melanogaster.

The zeste1 (z1) mutation of Drosophila melanogaster produces a mutant yellow eye color instead of the wild-type red. Genetic and molecular data suggest that z1 achieves this change by altering expression of the wild-type white gene in a manner that exhibits transvection effects. There exist suppressor and enhancer mutations that modify the z1 eye color, and this paper summarizes our studies of those belonging to the Suppressor 2 of zeste complex [Su(z)2-C]. The Su(z)2-C consists of at least three subregions called Psc (Posterior sex combs), Su(z)2 and Su(z)2D (Distal). The products of these subregions are proposed to act at the level of chromatin. Complementation analyses predict that the products are functionally similar and interacting. The alleles of Psc define two overlapping phenotypic classes, the hopeful and hapless. The distinctions between these two classes and the intragenic complementation seen among some of the Psc alleles are consistent with a multidomain structure for the product of Psc. Psc is a member of the homeotic Polycomb group of genes. A general discussion of the Polycomb and trithorax group of genes, position-effect variegation, transvection, chromosome pairing and chromatin structure is presented.

ATP-Binding Cassette Transporters↗
PubMed1998

Shyness and little boy blue: iris pigmentation, gender, and social wariness in preschoolers.

In recent years, researchers have uncovered a link between iris pigmentation and inhibition/social wariness among young children (e.g., Rosenberg & Kagan, 1987, 1989; Rubin & Both, 1989). In the present study, 152 Caucasian preschool-aged (Mage = 54.09 months, SD = 5.84) children (77 males) with either blue (n = 84) or brown (n = 68) eyes, were compared in terms of parental and teacher ratings of social wariness, social play, and aggression. A significant Eye Color x Gender Interaction was found in terms of indices of social wariness; blue-eyed males were rated as more socially wary than brown-eyed males, while blue- and brown-eyed females did not differ in this regard. These results supported the notion that eye color is a marker variable for social wariness in young children.

Aggression↗
PubMed1982

Structure of the Drosophila mutable allele, white-crimson, and its white-ivory and wild-type derivatives.

The white locus in Drosophila is required for a normal brick-red eye color; deletions of this locus result in a bleached-white eye color. The white-crimson (wc) allele of white was isolated as a partial revertant of another mutant white allele, white-ivory (wi), a mutation due to duplication of sequences within the white locus. The wc allele reverts at high frequencies to wild-type and wi phenotypes and generates white-eyed derivatives, including deletions with one endpoint at the white locus. We analyzed the structure of the wc allele by molecular cloning and by Southern blot analysis of genomic DNA and found that the wc phenotype results from the insertion of a 10 kilobase DNA sequence into the wi duplication. Five independent phenotypic revertants of wc to wi were examined, and in each case reversion was accompanied by apparently precise excision of the insertion. Reversion of wc to a wild-type phenotype in each of the six cases examined was mediated by excision of both the insertion and one copy of the wi duplication, restoring gene structure to wild-type.

Alleles↗
PubMed1981

Some non-auditory correlates of the hearing threshold levels of an aviation noise-exposed population.

In a retrospective analysis of data collected during the 1963 followup of the NAMRL Thousand Aviator Study, two hearing level groups were identified, normal and impaired, and compared along 33 non-auditory dimensions. It was discovered that these two equally noise-exposed groups could be differentiated according to their smoking history and eye color. That is, the impaired hearing group reported smoking more cigarettes for a greater period of time than did the members of the normal hearing group. Furthermore, blue-eye individuals were over-represented in the impaired hearing group and under-represented in the normal hearing group, whereas the reverse was true for brown-eyed aviators. This latter finding is consistent with reports linking temporary hearing loss and eye color. There was 31 other physical, psychological, and sociological measures which failed to appear differentially in the two groups.

Adult↗
PubMed2002

Sunburn, sunscreens, and phenotypes: some risk factors for cutaneous melanoma in southern Brazil.

BACKGROUND: The risk factors for cutaneous malignant melanoma have been studied in populations from numerous countries around the world. There are no published studies on the risk factors for this malignancy in Brazil, the largest country in South America. METHODS: A case-control study of all melanoma patients attending a university hospital in Porto Alegre, Brazil, was conducted over a 3-year period from 1995 to 1998. Phototype, hair and eye color, solar habits, history of sunburn, use of sunscreens, and the number of nevi were evaluated through a questionnaire and full body skin examination. Bivariate analysis and a logistic regression model were used to evaluate the data. RESULTS: One hundred and three malignant melanoma patients and 206 matched controls were enrolled in the study. The female to male ratio was 2 : 1. Light phototypes were more prone to the development of cutaneous melanoma. Although stronger in the bivariate analysis, in the logistic regression model, phototypes I or II and ephelides emerged only as moderate risk factors; light eye color and light hair color were not independently significant, with adjusted odds ratios (OR) close to zero. Commonly acquired nevi (CAN) showed a significant and strong effect in the bivariate analysis only when the "30 or more" category was compared to baseline. In the logistic regression model, the presence of a large number of CAN showed an association with increased levels of risk, although these findings did not reach classical significance. Dysplastic or atypical nevi seemed to contribute more strongly, although still with a moderate excess of relative risk. When the use of sunscreens was compared to no use at all, it appeared to show progressive protection as the solar protection factor (SPF) increased. Only SPF15 or greater (SPF15+) showed strong and significant protection when compared to baseline. Physical measures offered a weaker level of protection. Nevertheless, there was a significant increase in the risk of melanoma for those with a large number of sunburn episodes. It was found that 30 or more alleged episodes of sunburn showed a very strong OR of 11.4 (95% confidence interval, 2.6-50.5), the most significant in the study. CONCLUSIONS: Phototypes I and II, freckles, a large number of acquired nevi, dysplastic nevi, and inadequate photoprotection appeared as risk factors with moderate strength for cutaneous malignant melanoma in the studied population. The color of the eyes and hair showed a very weak statistical significance as a risk factor. Sunscreens showed progressive significance corresponding to an increase in SPF, the best scores in statistical protection being achieved in users of sunscreens with SPF15 or greater. Frequent sunburn episodes appeared as the most important risk factor associated with malignant melanoma in this sample of the white population in southern Brazil.

Adult↗
PubMed2003

A regressive model analysis of congenital sensorineural deafness in German Dalmatian dogs.

The objective of the present study was to analyze the mode of inheritance for congenital sensorineural deafness (CSD) in German Dalmatian dogs by consideration of association between phenotypic breed characteristics and CSD. Segregation analysis with regressive logistic models was employed to test for different mechanisms of genetic transmission. Data were obtained from all three Dalmatian kennel clubs associated with the German Association for Dog Breeding and Husbandry (VDH). CSD was tested by veterinary practitioners using standardized protocols for Brainstem Auditory-Evoked Response (BAER). The sample included 1899 Dalmatian dogs from 354 litters in 169 different kennels. BAER testing results were from the years 1986 to 1999. Pedigree information was available for up to seven generations. The segregation analysis showed that a mixed monogenic-polygenic model including eye color as covariate among all other tested models best explained the segregation of affected animals in the pedigrees. The recessive major gene segregated in dogs with blue and brown eye color as well as in dogs with and without pigmented coat patches. Models which took into account the occurrence of patches, percentage of puppies tested per litter, or inbreeding coefficient gave no better adjustment to the most general (saturated) model. A procedure for the simultaneous prediction of breeding values and the estimation of genotype probabilities for CSD is expected to improve breeding programs significantly.

Animals↗
PubMed2001

The interspecific origin of B chromosomes: experimental evidence.

A centric fragment was generated during the introgression of a chromosome region from Nasonia giraulti into N. vitripennis. This neo B chromosome carries the N. giraulti or 123+ gene for wild-type eye color. Using this phenotypic effect, the transmission of this chromosome was analyzed. The supernumerary chromosome showed less than Mendelian segregation rate in meiosis and some mitotic instability manifested as mosaic phenotype for eye color. However, transmission rate and mitotic stability increased over successive generations. The transmission rate through male gametogenesis was nearly 100%. These results support the interspecific hybridization model for B chromosome origin and reveal that problems in chromosome stability can persist for several generations after "foreign chromosomes" are introduced into a different species. We suggest that hybrid zones should be investigated as possible sites for neo-B chromosome generation.

Animals↗
PubMed1996

Structure and expression of wild-type and suppressible alleles of the Drosophila purple gene.

Viable mutant alleles of purple (pr), such as prbw, exhibit mutant eye colors. This reflects low 6-pyruvoyl tetrahydropterin (PTP) synthase activity required for pigment synthesis. PTP synthase is also required for synthesis of the enzyme cofactor biopterin; presumably this is why some pr alleles are lethal. The prbw eye color phenotype is suppressed by suppressor of sable [su(s)] mutations. The pr gene was cloned to explore the mechanism of this suppression. pr produces two PTP synthase mRNAs: one constitutively from a distal promoter and one in late pupae and young adult heads from a proximal promoter. The latter presumably supports eye pigment synthesis. The prbw allele has a 412 retrotransposon in an intron spliced from both mRNAs. However, the head-specific mRNA is reduced > 10-fold in prbw and is restored by a su(s) mutation, while the constitutive transcript is barely affected. The Su(s) protein probably alters processing of RNA containing 412. Because the intron containing 412 is the first in the head-specific mRNA and the second in the constitutive mRNA, binding of splicing machinery to nascent transcripts before the 412 insertion is transcribed may preclude the effects of Su(s) protein.

Alcohol Oxidoreductases↗