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Linkage between an X-chromosome marker (deutan color blindness) and bipolar affective illness. Occurrence in the family of a lithium carbonate-responsive schizo-affective proband.

Studies with X-chromosome markers in mental illness have been limited to the diagnostic concept of primary affective disorders. The present study is the first to our knowledge to demonstrate statistically measurable linkage between color blindness and manic-depressive illness in a family identified by a schizo-affective proband. Linkage data and lithium carbonate response in the proband suggest that the schizophreniform-affective spectrum in members of the pedigree may reflect a genetically distinct disorder. The use of a genetic marker as a heuristic diagnostic criterion in a subgroup of heredofamilial psychoses with unclear diagnostic boundaries is proposed.

Adult↗

Analysis of familial factors in bipolar affective illness.

Familial transmission of affective illness was studied using a family interview and family history method in a group of 35 bipolar manic-depressive patients. Morbidity risk for bipolar and unipolar affective illness in first-degree relatives is approximately 30% in this population. Probands with a positive family history for bipolar illness have a significantly greater risk for alcoholism in first-degree relatives. Four cases of father-to-son transmission are reported. Linkage of color vision deficiency or Xga blood group and affective illness within families could not be substantiated in our sample. We discuss evidence regarding the mode of transmission of affective illness.

Adult↗

Color blindness not closely linked to bipolar illness. Report of a new pedigree series.

A new pedigree series of bipolar manic-depressive patients admitted to the National Institute of Mental Health intramural research program was evaluated for linkage between bipolar illness and red-green color blindness, since previous studies had indicated that close linkage was generally present. Using family study methods, six informative pedigrees were investigated. Analysis was performed using a multigenerational procedure and taking into account variable penetrance. Close linkage could be definitively ruled out as a general finding. Bipolar and related illnesses are thus not generally transmitted by a single major gene close to the protan/deutan region of the human X-chromosome.

Bipolar Disorder↗

Color blindness linkage to bipolar manic-depressive illness. New evidence.

Linkage between protanopia and deuteranopia and bipolar manic-depressive illness is demonstrated in a sample of eight informative families ascertained in Brussels. Genetic heterogeneity of bipolar affective disorders is also shown in the present study. These results add new evidence to the hypothesis of X-linked dominant genetic transmission of affective liability in a subgroup of patients with bipolar affective disorders.

Adult↗

X-chromosome markers and manic-depressive illness. Rejection of linkage to Xq28 in nine bipolar pedigrees.

Numerous reports have been published concerning linkage of X-chromosome markers of the q28 region (including protan and deutan color blindness [CB] and glucose-6-phosphate dehydrogenase deficiency) to manic-depressive illness. We studied nine bipolar pedigrees (in which there was no male-to-male transmission) in an attempt to detect linkage, using three tightly linked polymorphic DNA loci, DXS15, DXS52 and F8C (factor 8 gene), all of which are closely linked to the CB and glucose 6-phosphate dehydrogenase classic Xq28 markers. Linkage to this region of Xq28 could be excluded unequivocally in these nine families. When these data were combined with our earlier series of bipolar pedigrees, informative for either protan or deutan CB, a total of 14 bipolar pedigrees have been studied, with no evidence of linkage or heterogeneity. At a recombination fraction (theta) of 1%, this series had greater than 95% power to detect linkage if only 50% of the pedigrees studied were linked to the CB region. Our failure to confirm the previously reported linkage of manic-depressive illness to the CB region of the X chromosome indicates that this linkage is not as common as previously suggested.

Bipolar Disorder↗

Impaired color vision in cocaine-withdrawn patients.

BACKGROUND: The main reinforcing effect of cocaine happens by altering dopaminergic neurotransmission in the brain reward systems. Dopamine is found in high concentrations in the retina in which it plays an important role in color vision. Therefore, we investigated whether cocaine-dependent patients might have impaired color vision. METHODS: We compared patients recently withdrawn from cocaine (n = 31) with matched normal controls (n = 31) on 2 color vision tests. RESULTS: Cocaine-withdrawn patients had significantly higher error scores than matched controls on the Farnsworth-Munsell 100-hue and Lanthony desaturated D-15 color vision tests. Also, 23 of the 31 cocaine-withdrawn patients had blue-yellow color vision losses on the Farnsworth-Munsell 100-hue test compared with 3 controls (P < .001, chi 2 test) and 15 had blue-yellow color vision loss on the Lanthony desaturated D-15 test compared with 2 controls (P < .001, chi 2 test). CONCLUSIONS: These significantly higher test error scores and blue-yellow color vision losses suggest that color vision is impaired in cocaine-withdrawn patients. Color vision testing may be useful in future studies of cocaine-dependent patients.

Adult↗

Genetic origins of the Japanese: a partial support for the dual structure hypothesis.

Based on the morphological characteristics of the skull and teeth, Hanihara ([1991] Japan Review 2:1-33) proposed the "dual structure model" for the formation of modern Japanese populations. We examine this model by dividing it into two independent hypotheses: 1) the Upper Paleolithic population of Japan that gave rise to the Neolithic Jomon people was of southeast Asian origin, and 2) modern Ainu and Ryukyuan (Okinawa) populations are direct descendants of the Jomon people, while Hondo (Main Island)-Japanese are mainly derived from the migrants from the northeast Asian continent after the Aeneolithic Yayoi period. Our aim is to examine the extent to which the model is supported by genetic evidence from modern populations, particularly from Japan and other Asian areas. Based on genetic distance analyses using data from up to 25 "classic" genetic markers, we find first that the three Japanese populations including Ainu and Ryukyuan clearly belong to a northeast Asian cluster group. This negates the first hypothesis of the model. Then, we find that Ainu and Ryukyuans share a group contrasting with Hondo-Japanese and Korean, supporting the second hypothesis of the model. Based on these results, we propose a modified version of the dual structure model which may explain the genetic, morphological, and archaeological evidence concerning the formation of modern Japanese populations.

Asia↗

Quantitative assessment of color vision impairment in workers exposed to toluene.

Color vision was examined by the Lanthony-D-15 desaturated test in two groups of workers occupationally exposed to toluene and in a control group. Biological parameters of toluene exposure were analyzed: toluene in air and in venous blood, orthocresol, and hippuric acid in urine after workshift. The first exposed group, Group E1, comprised 41 workers (toluene exposure ranged from 11.30 to 49.30 ppm), and the second exposed group, Group E2, comprised 32 workers (toluene exposure ranged from 66.00 to 250.00 ppm). The nonexposed group, Group NE, comprised 83 subjects. Each group was divided into two subgroups; alcohol consumers and nonconsumers. Color vision loss was expressed as a color confusion index (CCI) and as age and alcohol intake-adjusted color confusion index (AACCI). Significantly higher values of CCI and AACCI (both P < 0.0001) in Group E2 in comparison to Group NE, and significantly higher CCI (P < 0.0001) and AACCI (P < 0.05) values in Group E2 in comparison to Group E1 were established. The significant difference in CCI value between alcohol consumers and nonconsumers was established only in Group NE (P < 0.05). In Group NE significant correlation was found between CCI value as a dependent and age and alcohol intake as independent cofactors (R2 = 0.45; P = 0.0000). In Group E2 significant correlation was established between CCI as a dependent factor and age, toluene in air, and alcohol intake (R2 = 0.72; P = 0.0001), or between CCI as dependent and age, toluene in blood and alcohol intake as independent cofactors (R2 = 0.68; P = 0.0002). In Group E1 significant correlation was established only between CCI and age (P <0.005). In Group E2, AACCI value significantly correlated with toluene in air (P < 0.0001), toluene in blood (r < 0.0005), orthocresol (P < 0.005) and hippuric acid (P < 0.005) in urine after workshift. There were no differences between smokers and nonsmokers in CCI values in the examined groups. Results of this study indicate that toluene in exposed workers can impair color vision. The role of alcohol intake and age influence on color vision loss cannot be ignored in such workers.

Adult↗

Origin and distribution of Daltonism in Italy.

A research project was started in Italy in order to map dyschromatopsies in this country. Field data was collected by the authors in Liguria, Veneto, Emilia-Romagna, Apulia, Sicily, and by other authors in Lazio, Calabria, Basilicata, and Sardinia. The samples were all composed of more than 500 male subjects, of homogeneous origin, and assessed using the Ishihara (1973) and the Farnsworth (1947) tests. Statistical analysis identified two groups showing different mean percentages: one, coastal (n = 13,091; 6.50%) and the other, inland (n = 17,881; 5.21%). The results stimulated an ecological-ergonomic hypothesis based on nutrition (i.e., food gathering strategies) and the kind of light prevailing in the habitat. If trichromacy has been brought about by frugivore feeding (Polyach, 1957), dichromacy may have been maintained by giving a selective advantage to fishermen (originally fishing one fish at a time by hand). This is valid for both sea or fresh water habitats, characterized by blue-green prevailing light and with sharp discrimination for blue-gray shapes and colors (usually, 70% of dichromats are deutans). To support this hypothesis a field survey was carried out among 661 Sicilian traditional fishermen, which furnished the highest rates of dyschromatopsia in Italy: 7.90%. In conclusion, we can hypothesize that endogamous fishermen groups bordering the coastal areas of continents, searching for waters abounding in fish, could have determined a greater incidence of color blindness in the coastal regions, while exogamous marriages between fishermen and peasants contributed to the lower diffusion of the genes responsible in inland areas.

Color Vision Defects↗

Cumulative exposure to styrene and visual functions.

BACKGROUND: Results from a 1990-1992 longitudinal study of several reinforced plastics plants showed that for those workers whose styrene exposure had decreased, color vision (CV) improved; while near visual contrast sensitivity (CS) was poorer. METHODS: In 1999, we retested these visual functions in 18 workers with good visual acuity. A cumulative exposure index (CEI), corrected for respirator use, was calculated for each worker. RESULTS: Intra-individual comparison of mandelic acid (MA) showed a significant decrease over time (Friedman; P = 0.015), but current values were not related to CEI. For CV, no significant difference was observed between 1992 and 1999; present results were not related to MA or CEI. The CS profile decreased over time, with significant differences at 3 cpd (Friedman; P < 0.05). CS did not vary with MA levels, but was significantly depressed at the intermediate frequencies among those in the upper CEIH category (Kruskal-Wallis; P < 0.05). CONCLUSIONS: These findings suggest that CS loss increases with long-term cumulative exposure, reflecting chronic damage to the neuro-optic pathways.

Adult↗

Impairment of color vision among workers exposed to low concentrations of styrene.

A field study was conducted among 21 male workers exposed to styrene of concentration below 30 ppm in a fiber-reinforced plastic boat manufacturing plant. Twenty-one male workers with similar age groupings, years of education, and social and occupational state served as referents. The mean end-of-shift urinary mandelic acid (MA) and phenylglycoxylic acid (PGA) for the exposed workers were 84 mg/g creatinine and 66 mg/g creatinine, respectively. The Lanthony D-15 Hue Desaturated Panel was used to evaluate color discrimination of the exposed and referent groups. The results of the test were expressed as total color difference score (TCDS). The exposed workers' mean TCDS (a higher score denotes poorer color discrimination ability) was significantly (p < 0.0006) higher than the referents'. Neurobehavioral tests were also conducted, using the World Health Organization's Neurobehavioral Core Test Battery (NCTB). All the results of the NCTB were poorer for the exposed than for the referents. However, significant differences were observed only for Digit Span, Digit Symbol, and Benton Visual Retention tests. These results suggest that low exposure to styrene could affect some psychometric performance and may impair color vision.

Adult↗

Brief report: linkage between G6PD and fragile-X syndrome.

Eighteen Sardinian pedigrees segregating for the X-fragile site syndrome were studied with respect to the segregation of the fragile site (FS) at Xq28, mental retardation, and macro-orchidism. No exception was found in the association of this symptomatic triad (MOM-X) in 41 out of 42 patients examined. The exceptional individual had micro- rather than macro-orchidism and was found to have a 47, XXY sex chromosome complement. In six informative sibships, the MOM-X syndrome was found to segregate in close linkage association with G6PD-deficiency or protan colorblindness. The maximum likelihood estimate of recombination if 6% with 90% fiducial limits between 2.5 and 19.5% and an odds ratio in favor of measurable linkage of 428:1. However, no hint of measurable linkage was found in six pedigrees segregating for G6PD and the Renpenning syndrome or other unspecified types of X-linked mental retardation. These data give strong support to the generally held hypothesis that the FS at Zq28, characteristic of the MOM-X syndrome, is a direct expression of a genetic change in the same chromosomal region. They also clearly suggest that X-linked MR without FS may be the result of different allelic mutations at the same locus.

Color Vision Defects↗

Linkage analysis of bipolar illness with X-chromosome DNA markers: a susceptibility gene in Xq27-q28 cannot be excluded.

Transmission studies have supported the presence of a susceptibility gene for bipolar (BP) illness on the X-chromosome. Initial linkage studies with color blindness (CB), glucose-6-phosphate dehydrogenase (G6PD) deficiency, and the blood coagulation factor IX (F9) have suggested that a gene for BP illness is located in the Xq27-q28 region. We tested linkage with several DNA markers located in Xq27-q28 in 2 families, MAD3 and MAD4, that previously were linked to F9 and 7 newly ascertained families of BP probands. Linkage was also examined with the gene encoding the alpha 3 subunit of the gamma-amino butyric acid receptor (GABRA3), a candidate gene for BP illness located in this region. The genetic data were analyzed with the LOD score method using age-dependent penetrance of an autosomal dominant disease gene and narrow and broad clinical models. In MAD3 and MAD4 the multipoint LOD score data suggested a localization of a BPI gene again near F9. In the 7 new families the overall linkage data excluded the Xq27-q28 region. However, if the families were grouped according to their proband's phenotype BPI or BPII, a susceptibility gene for BPI disorder at the DXS52-F8 cluster could not be excluded.

Adolescent↗