PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Eye Color”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,045 records · Page 58Linked to original sources
PubMed1979

The problem of determining twin zygosity for epidemiological studies.

The use of epidemiological studies of twins as a means of determining the existence of genetic factors in various conditions is well known. To be of value, the zygosity of the twin pairs must be identified with as great a degree of confidence as possible. A method of determining twin zygosity, using concordance in general likeness, hair colour, hair type, eye colour, ear form, tongue roll and phenylthiocarbamide (PTC) taste sensitivity, was developed for use in a survey of 244 pairs of like-sexed twins aged 5 to 15 years. The results obtained and the problems raised when applying this method are discussed. The method was sinple to apply to a large group of twin pairs, and monozygotic pairs were identified with a degree of confidence greater than 95%.

Adolescent↗
PubMed1992

Expression of cis-regulatory mutations of the white locus in metafemales of Drosophila melanogaster.

At the white eye colour locus, there are a number of alleles that have altered expression between males and females. To test these regulatory mutations of the white eye colour locus for their phenotypic expression in metafemales (3X; 2A) compared to diploid females and males, eleven alleles or transduced copies of white were analysed. Two alleles that exhibit dosage compensation between males and females (apricot, blood) also exhibit dosage compensation in metafemales. White-ivory and white-eosin, which fail to dosage compensate in males compared to females, but that are distinct physical lesions, also show a dosage effect in metafemales. Two alleles with greater expression in males than females (spotted, spotted-55) exhibit even lower expression in metafemales. Lastly, five transduced copies of white carrying three different lengths of the white promoter, but that all exhibit higher expression in males, show reduced expression in metafemales, exhibiting an inverse correlation between the level of expression and the dosage of the X chromosome. Because these alleles of white respond to dosage compensation in metafemales as a continuum of the male and female responses, it is concluded that the same basic mechanism of dosage compensation is involved and that the dosage of the X chromosome conditions the sexually dimorphic expression.

Alleles↗
PubMed1993

Dosage dependent modifiers of white alleles in Drosophila melanogaster.

As part of a study to identify dosage-sensitive modifiers of the white eye colour locus and the retrotransposon, copia, a segmental aneuploid screen was conducted. It surveys the autosomal complement of the genome for dosage dependent modifiers of white, including ones effective upon retrotransposon insertion-induced alleles. Several regions were found which, when present as a segmental trisomy, affected one or more of the alleles tested in a strong and consistent fashion. Two of these regions have been identified as containing previously described modifiers, Darkener-of-apricot and Inverse regulator-a. The remainder identify new white allele modifiers. Selected segmental monosomics were also tested where possible for regions exhibiting a trisomic effect. At least three regions were found to have a dosage-dependent effect in one, two and three copies.

Alleles↗
PubMed1996

Natural repressors of P-induced hybrid dysgenesis in Drosophila melanogaster: a model for repressor evolution.

Type I repressors control P element transposition and comprise full length elements and elements with small 3' deletions in the final exon. Using a sensitive assay for measuring the strength of repression of P element transposition in somatic and germline tissues, we have isolated and characterized a naturally occurring type I repressor element from a Q population of Drosophila melanogaster. We demonstrate that the almost complete repression of transposition in this population is a mixture of KP elements with intermediate levels of repression, and the strong contribution of a single 2.6 kb P element deletion derivative, which we call SR (Strong Repressor). A deletion in the final intron of SR allows for the constitutive production of a putative 75 kDa repressor protein in germline tissues in addition to the production of the 66 kDa repressor in the soma, which would result in a biparental mode of inheritance of repression. Based on the four observed classes of natural Q populations, we propose a model in which populations containing SR-like elements, capable of producing strong type I repressor constitutively, have a selective advantage over populations which rely either on maternally transmitted P cytotype or on KP-induced weak levels of repression. Such populations may subsequently spread and constitute an evolutionary stable strategy for the repression of hybrid dysgenesis in Drosophila melanogaster.

Amino Acid Sequence↗
PubMed1991

Ototoxicity of cis-platinum and its relationship to eye colour.

The following hypothesis is presented: that the susceptibility of an individual patient to hearing loss as a result of cis-platinum administration can be predicted on the basis of eye colour. The rationale is that the melanin content of the inner ears is related to that of the eyes; dark eyes contain more melanin than light-coloured eyes; and melanin causes the accumulation of the ototoxic drug within the inner ear. Hence those with dark eyes will suffer greater damage to the hearing than those with pale eyes. An investigation that confirmed this hypothesis is reported. In addition to cochlear damage there is a significant likelihood of damage to the auditory nerve as a result of the treatment.

Adult↗
PubMed1995

Cisplatin in children: hearing loss correlates with iris and skin pigmentation.

Pigmentation is reported to affect cisplatin-induced ototoxicity in adult humans. The hearing loss is worse in people with brown irises, than in those with blue irises. We assessed the hypothesis that cisplatin-treated children with dark irises suffer more deterioration in auditory thresholds than do those with less pigmentation. For the 19 children whose data met the requirements of this observational retrospective study, we found a weak correlation (Spearman's r = 0.50; p < 0.05) of high frequency hearing loss (at 4000 Hz) and pigmentation. Blue or hazel-eyed children averaged 2.9 dB worsening at 4000 Hz, in contrast to 14.2 dB worsening for brown or black-eyed children. Pigmentation may account for some of the individual susceptibility to cisplatin ototoxicity. We suggest that iris colour be included in future reports of cisplatin-related hearing loss.

Adolescent↗
PubMed2001

Determinants of melanoma in a case-control study of twins (United States).

OBJECTIVES: To estimate the relative contribution of environmental and genetic factors disposing towards the development of melanoma. METHODS: We investigated risk factors for melanoma in a case-control study conducted among 185 North American twin pairs in which one was diagnosed with melanoma and the other (the co-twin of the case) was not. We considered monozygous (MZ) and dyzygous (DZ) twins separately. RESULTS: While greater risk of melanoma was associated with number of large nevi in DZ twins (adjusted OR = 26.6 (4.2-170.8) for three or more large moles), this was not the case for MZ twins (adjusted OR = 1.4 (0.6-3.2) for three or more large moles). Elevated risks of developing melanoma with site-specific sun exposures resulting in sunburn also appeared to be confined to DZ twins. Despite the number of identical twins reporting a difference in mole prevalence, we observed only a modest and inconsistent increase in melanoma risk attributable to that factor, whereas the increase within fraternal twin pairs was larger by an order of magnitude. CONCLUSIONS: If confirmed, this indicates that the significance of mole prevalence as a risk factor for melanoma is largely as a genetic, rather than an environmental, factor. We noticed an increased risk of developing melanoma among DZ twins who drank moderate amounts of beer, but we believe this result may be due to the sun-exposure activities of those people most likely to drink moderate amounts of beer.

Adolescent↗
PubMed2003

[Genetic counseling and DNA testing in patients with increased risks for malignant melanoma].

There are numerous risk factors for the development of malignant melanoma. It has been documented that genetic predisposition exists but exogenous factors are also very important. In familial melanomas it has been well established that mutation in the CDKN2A gene which is located at chromosome 9 leads to a marked risk for malignant melanoma. This tumor-suppressor gene is important for the regulation of the cell cycle and mutation in this gene is associated also with an increased rate of pancreas cancer. The penetrance of this mutation is influenced by UV-energy. In addition it has been shown that a second cluster for the familial atypical nevus syndrome is located at chromosome 1p36. Patients with the rare disease xeroderma pigmentosum have a defect in the DNA-repair mechanism inherited in an autosomal recessive trait and therefore develop within the first 20 years of life numerous malignant skin tumours including malignant melanomas. But also in non-syndromic patients a decrease of DNA-repair ability may occur. It has been shown recently that reduced DNA-repair ability is an independent risk factor for malignant melanoma and may contribute to susceptibility to sunlight-induced melanoma among the general population. Other constitutional risk factors for the development of malignant melanoma are fair skin, red hair and blue eyes. The most important exogenous risk factor is UV-exposition. Extensive and repetitive sunburns before the age of 15 years are especially predisposing to malignant melanoma. The most important preventive measures are continuous sun-protection including avoidance of sun in noon time on tropical and subtropical places, wearing a hut and sunglasses and application of sun-screens with high sun-protection factor. Furthermore a regular check for changing moles is indicated in persons with multiple atypical nevi or a familial melanoma syndrome. Nowadays molecular genetic screenings are available within research projects for members of melanoma-prone families. The controversy of such possibilities is discussed.

Adolescent↗
PubMed2003

Transcription of prostanoid receptor genes and cyclooxygenase enzyme genes in cultivated human iridial melanocytes from eyes of different colours.

Several prostaglandin analogues used for glaucoma treatment have been shown to cause increased iridial pigmentation as side-effect. In the present study we identified the types of prostanoid receptors and cyclooxygenase (COX) enzymes that are expressed in human iridial melanocytes isolated from eyes of different colours. Iris specimens were obtained during trabeculectomy surgery, or from enucleated eyes, and the iridial melanocytes were isolated and cultivated. The transcription of the DP, EP1, EP2, EP3, EP4, FP, IP and TP prostanoid receptor genes as well as the COX-1 and COX-2 enzyme genes was investigated using reverse transcriptase-polymerase chain reaction (RT-PCR). Of the prostanoid receptors the FP receptor gene was found to be most consistently transcribed in the melanocytes isolated from both blue- and hazel-coloured eyes. No RNA of the DP, EP2 and TP receptor genes could be detected, whereas the EP1, EP3, EP4 and IP receptor genes were found to be transcribed in melanocytes from some eyes. The COX-2 gene was found to be transcribed, but the COX-1 gene less consistently. There was no difference in gene transcription pattern between melanocytes originating from eyes treated with latanoprost, and eyes not previously treated with the prostaglandin. These results indicate that the FP prostanoid receptor gene is transcribed in cultivated human iridial melanocytes of both blue and hazel eyes, whereas the other prostanoid receptor genes seem to be transcribed much less frequently, or not at all. Surprisingly, the COX-2 rather than the COX-1 gene, was found to be transcribed in the melanocytes.

Aged↗
PubMed1999

Sperm competition between Drosophila males involves both displacement and incapacitation.

Females in almost all animal groups copulate with multiple males. This behaviour allows different males to compete for fertilization and gives females the opportunity to mediate this competition. In many animals and most insects, the second male to copulate with a female typically sires most of her offspring. In Drosophila melanogaster, this second-male sperm precedence has long been studied but, as in most species, its mechanism has remained unknown. Here we show, using labelled sperm in doubly mated females, that males can both physically displace and incapacitate stored sperm from earlier-mating males. Displacement occurs only if the second male transfers sperm to the female, and in only one of her three sperm-storage organs. Incapacitation can be caused by either fertile or spermless second males, but requires extended intervals between matings. Sperm from different males are not 'stratified' in the storage organs but mix freely. Many animal species may have multiple mechanisms of sperm competition like those observed here, and revealing these mechanisms is necessary to understand the genetic and evolutionary basis of second-male sperm precedence in animals.

Animals↗