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PubMedDate not supplied

Genetic linkage between X-chromosome markers and bipolar affective illness.

A pedigree study shows close linkage of bipolar affective illness (manic depression) to the X-chromosome markers colour blindness and glucose-6-phosphate dehydrogenase deficiency. The maximum lod score ranges from 7.52 (assuming homogeneity) to 9.17 (assuming heterogeneity); that is, the odds in favour of linkage range between 3 X 10(7) to 1 and 10(9) to 1. These results provide confirmation that a major psychiatric disorder can be caused by a single genetic defect. As a possible first step in characterizing the primary genetic abnormality, this finding may have important implications for the aetiology, nosology, pathophysiology and, possibly, prevention and treatment of bipolar affective disorder. It also provides a means for identifying and characterizing homogeneous populations of patients and may help in clarifying aetiological heterogeneity.

Bipolar Disorder↗
PubMed1991

Electroretinograms in patients with achromatopsia.

Eleven patients with X-linked and 9 patients with autosomal recessive achromatopsia were examined with full-field electroretinograms. In the standard full-field ERG's, normal rod responses were obtained, but the amplitude of the cone b-waves was not detectable. With computer averaging and narrow bandpass filtering, residual cone b-wave responses could be detected in 10 of the 20 patients. The residual cone b-wave amplitudes were markedly different in the 3 families with X-linked achromatopsia. In two of them, residual cone b-wave responses were seen in all patients examined. In contrast, such responses were seen only in 2 of 7 patients in the third family. There were also differences in other clinical observations (mainly in the visual acuity and refractive error) and we therefore suggest that there are at least two forms of X-linked achromatopsia. The ratios of the cone response amplitudes to 30 Hz flickering orange and blue-green light suggested that the defect in the X-linked achromatopsia patients was of the protanope type, whereas in the autosomal patients, both the protanope and the deutanope type was seen. In conclusion, measurements of the residual cone b-wave amplitude responses are of diagnostic and may possibly be of prognostic value when examining children and other members of families with achromatopsia.

Adult↗
PubMed1980

Central achromatopsia: behavioral, anatomic, and physiologic aspects.

The neuropsychologic, neuroanatomic, and neurophysiologic correlates of achromatopsia were studied in two patients. Prosopagnosia accompanied the color perception defect in the bilateral case but not in the unilateral one. No other neuropsychologic disturbance was present in either case. The lesions compromised the ventromedial sector of the occipital lobe in both cases. Cerebral evoked responses produced by pattern shift stimulation were normal for black and white but abnormal for red and green, when stimulation was given in the achromatopsic field.

Cerebral Infarction↗
PubMed1988

Diagnosis of dominant infantile optic atrophy in early childhood.

An acquired tritan defect is the earliest and the most pathognomonic sign of dominant infantile optic atrophy (DIOA) and the Tritan Album of Lanthony (1985) is helpful for the diagnosis of this condition. In preschool children, diagnosis of DIOA is possible by modifications of this test, using one plate under standard illumination which can be rotated into four positions, and by measuring the maximum distance of recognition of the plate.

Adult↗
PubMed1983

Discrepant results obtained with two versions of the Farnsworth Panel D-15 test in patients with acquired blue-yellow defects.

Two commercially available Panel D-15 tests were administered to two patients with acquired blue-yellow defects. The results obtained with each test were different and apparently influenced by the cap construction which is the only difference between the two tests. In one test the surface of the cap is concave and polished while in the other test the cap surface is flat and has a matte or dull finish. The mechanism accounting for the different results is not obvious.

Adult↗
PubMed1978

Central representation of colour vision deduced from studies on a subject with a central colour vision defect.

M.W.'s grossly defective responses to red light stimuli are caused by an abnormality of central vision which is highly specific in its action. The abnormal activity does not affect stereoscopic function and only partially modifies the parametric characteristics of the contrast threshold elevation effect. These experimental observations lend support to the concept of parallel processing of different attributes of the visual stimulus, possibly by different cortical areas. We suggest that understanding of central visual processes could be facilitated by further studies on subjects with malfunction of the visual cortex.

Adult↗
PubMed1980

A model for colour vision defect.

The Unique Green phenomenon whereby the wavelengths of light which are judged neither blue-green nor yellow-green show a distinct genetic polymorph. Amongst the males there is a clear bimodality whereas there is a near normal distribution amongst the females. The classification of the types of person so produced breeds true apparently in the X-chromosome. This phenomenon now having been confirmed is impossible to fit into the strict Walraven model of colour vision without modification. The modification that would be used is discussed and it is shown that a number of other difficulties within the Walraven model model can also be resolved.

Color Perception↗
PubMed1971

Hypogonadotropic hypogonadism in patients with multiple congenital defects.

Several syndromes have been reviewed in which hypogonadotropism is associated with multiple somatic and neurologic anomalies. A review of the literature indicates that these conditions demonstrate considerable clinical heterogeneity. In the several hypogonadotropic syndromes described to date autosomal and X-linked transmission have been implicated in the inheritance of the hypogonadism. The associated neurologic and somatic anomalies may segregate independent of the hypogonadism and in some instances may have a separate mode of transmission.

Abnormalities, Multiple↗
PubMed1977

Cone pigments in human deutan colour vision defects.

1. The Nagel anomaloscope, neutral points and dichromatic matches to a spectral green light identified a population of seventy red-green dichromats. 2. The anomaloscope settings allow the calculation of the relative action spectrum of the match at the wave-length of the red (645 nm) and green (535 nm) primaries. The distribution of this ratio is bimodal; there are two clusters with a gap of about 0-75 long units between. Among the thirty-eight deuteranopes there are wide differences in anomaloscope matches; similar differences appear among the thirty-two protanopes. 3. Retinal densitometry of the foveas of fifteen of the deuteranopes is compared and contrasted with measurements on trichromats. In the former, only one photolabile pigment is found in the red-green region of the spectrum; normals always have two. The view of Rushton (1965a) that deuteranopes have erythrolabe but no measurable chlorolabe is confirmed for each member of this group. 4. Simple deuteranomalous show two red-green cone pigments. The difference spectra of extreme deuteranomalous are very similar to those found in deuteranopia. 5. Individual differnce in kinetics (photosensitivity, time constant of regeneration) and in the density and lambdamax of the difference spectrum of erythrolabe in deuteranopia are appreciable; the reasons for these differences are not clear.

Color Vision Defects↗
PubMed1998

Colour constancy impairments in patients with lesions of the prestriate cortex.

Colour matching and colour constancy were studied in seven patients and 46 control subjects. Subjects were required to match Munsell Colour Chips presented under either identical or different illumination. Three of the patients had deficits in colour constancy, i.e. failure to compensate for the change in the wavelength composition of the illumination. Two of the patients with defective constancy had suffered bilateral cortical damage to the posterior lingual and fusiform gyri, and one patient had a lesion restricted to the same regions of the right hemisphere. Our observations indicate that these cortical areas, which include part of putative human area V4, play an important role in colour constancy.

Adult↗
PubMed1985

The Boström-Kugelberg pseudo-isochromatic plates. How efficient is the third edition?

The third edition of the Boström-Kugelberg pseudo-isochromatic plates was printed to the best possible visual match with the second edition. Slight colour differences between the 2 editions initiated this study where 72 colour defectives and 57 normal trichromats were tested with the plates and classified with the aid of Nagel's anomaloscope. Of the defectives, the plate test disclosed all but two anomalous trichromats. One normal subject was falsely classified as defective. The plates had to be shown twice according to the instructions since otherwise 13 of the 53 normals were misclassified. Three plates were shown to have low sensitivity; one is best used as a demonstration plate, and the other two can be deleted without lost efficiency. Forty-eight of the colour defectives were also studied with Farnsworth's lantern. The correlation between the numbers of plate and signal errors was weak. All subjects who failed the lantern test made several plate errors, but 15 subjects who passed the lantern test, made two or more errors on the plate test. The outcome of the plate test does not give evidence of the subject's lantern test performance.

Adolescent↗
PubMed2001

Video color perimetry: impairment in glaucoma suspects.

PURPOSE: To detect mild visual field impairment in asymptomatic glaucoma suspect patients. METHODS: Color perception within the visual field was tested with customized color video perimetry. The key features of the system were stimuli color desaturation, low-level luminance and equiluminant gray background. Twenty patients with asymptomatic glaucoma were tested and compared with a group of age-matched control subjects. RESULTS: Automated perimetry test findings differed significantly in the two groups, particularly for short-wavelength sensitivity (blue). The severity of color impairment correlated directly with intraocular pressure. CONCLUSION: Desaturated low-luminance video perimetry will reliably detect and quantify asymptomatic visual field defects. A previous work on multiple sclerosis has detected a mild long-wavelength (red) impairment in asymptomatic patients after an episode of optic neuritis, even in clinically unaffected fellow eyes. Our findings in glaucoma suspect patients indicate that a mild blue impairment could be the initial sign of this disease.

Adult↗
PubMed2001

Chromatic and achromatic defects in patients with progressing glaucoma.

To evaluate the pattern of losses associated with glaucomatous injury in patients with progressing glaucoma, functional losses were examined in 14 patients with progressing glaucoma using tests for which detection should be selectively mediated by one of three psychophysical mechanisms. Red-on-white increments, blue-on-white increments and critical flicker frequency were used to isolate the responses of the red-green chromatic mechanism, the blue-on chromatic mechanism, and the high-frequency flicker achromatic mechanism. For our 3.1 degrees circular stimuli, chromatic defects were found in a greater number of the patients with glaucoma than were achromatic defects. We evaluated these defects in terms of two existing hypotheses: preferential loss and reduced redundancy. The greater sensitivity to glaucomatous injury of chromatic tests, compared to achromatic tests, found in this and other studies and the apparent discrepancy between anatomical and psychophysical studies can be parsimoniously explained by differences in cortical summation of ganglion cell responses for the chromatic and achromatic pathways.

Aged↗
PubMed2004

Confessions of a colour blind physician.

The author describes his experiences due to his inherited colour vision deficiency, as a child, as student and as a medical practitioner, when he had certain difficulties in clinical work. He quotes from the literature on the clinical skills of physicians with this deficiency and gives an account of his own research that involved meeting and testing other doctors of medicine. This revealed a wide range of difficulties experienced by colour vision defective doctors in their practice of medicine with a potentiality for errors. Although there is a number of publications on this subject, the profession has made little response to them. This suggests that it is facing a dilemma that is inhibiting appropriate action. It is suggested that colour vision scientists and medical practitioners need more understanding of each other's discipline if progress is to be made. The advantages of screening of medical students and advising those found to have a deficiency are discussed and lines of research are proposed.

Attitude of Health Personnel↗
PubMed1997

Refinement of the locus for autosomal dominant juvenile optic atrophy to a 2 cM region on 3q28.

Juvenile optic atrophy (Kjer type; OPA1) is an autosomal dominant trait with an insidious onset in the first decade of life. The condition is characterized by a progressive loss of visual acuity that usually occurs with severe defects in color vision and visual fields. Genetic linkage analysis of a number of families has already assigned the OPA1 locus to the 3q28-qter region, within an estimated region of about 8 cM that is flanked by D3S1601 and D3S1265. Our study of a four-generation English family also supported tight linkage between the OPA1 locus and a group of DNA markers from the reported region. Of the 13 markers genotyped in this family, D3S2305 provided the maximum LOD score of 3.91 at theta = 0.00. Inspection of the haplotype transmission in this family identified critical recombinant individuals that refined the location of the OPA1 locus to an estimated region of about 2cM that is flanked by two DNA markers of D3S1601 and D3S2748. This refinement should facilitate the molecular cloning of the OPA1 gene and the determination of its defective product.

Alleles↗
PubMed1981

Color matching in autosomal dominant tritan defect.

We evaluated color matching in 39 observers with an autosomal dominant tritan defect. Eleven tritans were dichromats with 1 degrees field, and only two were dichromats with an 8 degrees field. Twenty-one of the tritan observers ahd normal blue-green equations with an 8 degrees field, indicating that autosomal dominant tritans have short-wavelength-sensitive cones. Some of the tritan observers showed a shifted blue-green equation, which was ascribed to rod activity.

Adolescent↗
PubMed1989

Use of the Farnsworth-Munsell 100-Hue test in the examination of congenital colour vision defects.

Results for the Farnsworth-Munsell 100-Hue test are reported for 238 male subjects with congenital colour vision defects (47 protanopes, 17 protanomalous trichromats, 57 deuteranopes and 117 deuteranomalous trichromats). The results are analysed in terms of the error score and the presence of an axis of confusion. A wide range of results is obtained in each diagnostic group and the error score cannot be used to distinguish between dichromats and anomalous trichromats. Approximately 50% of subjects with anomalous trichromatism obtain error scores less than 100 without an axis of confusion. These subjects could be mistakenly identified as having normal colour vision if pseudoisochromatic and colour matching tests are not employed. The prime use of the F-M 100 Hue test is in vocational guidance.

Adolescent↗
PubMed1985

Color mixture thresholds measured on a color television--a new method for analysis, classification and diagnosis of neuro-ophthalmic disease.

A color television display can be used to determine color and brightness discrimination thresholds using identical adaptation conditions and experimental technique. The color discrimination threshold is measured by using an equiluminous test spot--i.e. one which differs in color from the surrounding screen but has the same luminance. Because there is no brightness clue, the subject is forced to detect such a spot by using color discrimination. It is shown how color and brightness thresholds may be determined from threshold measurements of different color-mixtures even though it is not known beforehand which stimulus will be equiluminous for the subject. Results are shown for normal subjects, congenital color defectives and for two patients having optic nerve disease who show respectively non-selective and selective loss of color discrimination compared to brightness discrimination. Normal control data are presented, illustrating the effect of eccentricity, optical blur, viewing distance, pupil size and age. It is concluded that the technique is relatively insensitive to moderate variations in these factors and that it is more sensitive in detecting selective color loss than a spectral sensitivity technique which has been described previously.

Adult↗