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Frequencies of protan and deutan alleles in some Israeli communities and a note on the selection-relaxation hypothesis.
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Hydrogen cyanide and phenylthiocarbamide sensitivity, mid-phalangeal hair and color blindness in Yucatán, Mexico.
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Anomals and anopes among Beduin of Southern Sinai.
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P.T.C. thresholds, blood factors, colour vision and fingerprints of Jivaro Indians in Eastern Ecuador.
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Color blindness among Aymara in Chile.
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Ugandan colorblinds revisited.
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A genetic study on the Newards of Nepal valley.
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Anomalous color vision in three Mexican populations.
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The incidence of red-green colourblindness in the populations of Tripolitania, Cyrenaica and Fezzan in Libya, and of the Kikuyu, Kamba, Taita, Taveta and Luo tribes of Kenya.
The results of surveys of colourblindness carried out using the Ishihara test cards in Libya and Kenya, involving 384 and 504 individuals respectively, are reported. The Libyan samples, drawn from three geographically distinct regions of the country, are relatively homogeneous. The Kenyan samples, on the other hand, are heterogeneous, but in toto they display a markedly lower colourblindness percentage than do the Libyans. The Kenyan data are in broad accord with the other data available for sub-Saharan African populations. There are very few sets of comparative data available for North African populations, but the Libyan material displays a lower incidence of colourblindness than the values reported in European populations.
Impairment of retinal increment thresholds in Huntington's disease.
We have investigated detection thresholds for a foveal blue test light using a Maxwellian view system in 61 normal subjects, 19 patients with Huntington's chorea, 14 patients with Tourette's syndrome, and 20 patients with schizophrenia. Ten measurements were made: The blue test light (1 degree diameter, 500 msec duration) was presented either superimposed on a yellow adaptation field (5 degree diameter) or 500 msec after switching off this field (transient tritanopia effect). In both cases five different background intensities were presented. The only abnormality found was in patients with Huntington's chorea. During adaptation these patients' thresholds are significantly higher than normal (p < 0.005). No change was found in the transient tritanopia effect. Huntington's disease causes degeneration of several different transmitter systems in the brain. Increment threshold testing allows for noninvasive investigation of patients and confirms the involvement of the retina in the degenerative process in Huntington's chorea.
Psychological deficit in schizophrenia.
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Description of X-linkage pedigrees.
A description of the pedigrees informative for linkage with X-chromosome markers used as part of the affective disorders workshop is given.
Description of Amish Study data set.
A brief description is given on the ascertainment methods and diagnostic procedures for bipolar affective disorder patients and their relatives in Amish pedigrees. Data on a sample of five bipolar families are provided, including conventional blood typings, serum protein and RFLP data.
Linkage data on affective disorders in an epidemiologic context.
Recent data on chromosomal linkage markers in affective disorders indicate that single locus inheritance is involved in these disorders. The presence of a single locus has not been detectable using segregation analysis on family study data from large populations, possibly because of both heterogeneity and birth cohort and sex differences in diagnostic frequencies.
Utility of the affected sib pair method to detect linkage of a sex-linked dominant disease with a sex-linked recessive trait.
Use of affected sib-pairs for linkage determination of a sex-linked dominant disease with a recessive X-chromosome marker will require extremely large sample sizes, particularly when the marker is marginally polymorphic. In addition, this method should not be used without caution on data collected for a traditional LOD score analysis, without considering the parental mating types involved in the informative families. Nevertheless, ascertainment adjustment and correction for dependence of multiple pairs of affected sib-pairs in families suggests that this method provides linkage inference concordant with that of the traditional LOD score analysis.
Summary measures for evaluating the evidence for linkage.
Two summary measures for evaluating the evidence for linkage are the maximum lod score and the average of the likelihood function (antilod score). The average antilod score can be used to calculate an exact probability of there being no linkage. Use of subjective prior probabilities in the calculation will only influence the final conclusion in any important way if evidence from the sample is not particularly conclusive. It is shown how results from two-point analyses for linkage of the test locus with each marker locus can be easily combined to give an approximate probability of there being no linkage. Some examples using bipolar affective disorder data and marker loci are presented.
Cone cGMP-gated channel mutations and clinical findings in patients with achromatopsia, macular degeneration, and other hereditary cone diseases.
Unrelated patients with achromatopsia, macular degeneration with onset under age 50 years, cone degeneration or dysfunction, cone-rod degeneration, or macular malfunction were screened for mutations in the three genes known to be associated with achromatopsia: the GNAT2 gene encoding the alpha subunit of cone transducin and the CNGA3 and CNGB3 genes encoding the alpha and beta subunits of the cone cGMP-gated cation channel. We found no examples of patients with GNAT2 mutations. Out of 36 achromats, 12 (33%) had mutations in CNGA3 (13 different mutations including five novel mutations) and 12 (33%) had mutations in CNGB3 (six different mutations including four novel mutations). All achromats with CNG mutations had residual, presumably cone function as determined by computer-averaged 30-Hz electroretinograms (ERGs). There was considerable variability in acuity and color vision, with most patients having acuities of 20/200-20/400 and complete absence of color perception, and others having acuities of 20/25-20/40 and some color vision. Two pseudodominant achromatopsia cases were uncovered, both with CNGA3 mutations, including one family in which some compound heterozygotes with achromatopsia mutations were clinically unaffected. We found two novel CNGB3 changes in three patients with juvenile macular degeneration, a phenotype not previously associated with mutations in the cone channel subunits. These patients had subnormal acuity (20/30-20/60), normal to subnormal color vision, and normal to subnormal full-field cone ERG amplitudes. Our results indicate that some patients with channel protein mutations retain residual foveal cone function. Based on our findings, CNGB3 should be considered as a candidate gene to be evaluated in patients with forms of cone dysfunction, including macular degeneration.