AIM: To perform a detailed clinical and psychophysical assessment of the members of three British families affected with blue cone monochromatism (BCM), and to determine the molecular basis of disease in these families. METHODS: Affected and unaffected members of three families with BCM were examined clinically and underwent electrophysiological and detailed psychophysical testing. Blood samples were taken for DNA extraction. The strategy for molecular analysis was to amplify the coding regions of the long wavelength-sensitive (L) and middle wavelength-sensitive (M) cone opsin genes and the upstream locus control region by polymerase chain reaction, and to examine these fragments for mutations by direct sequencing. RESULTS: We have confirmed the reported finding of protan-like D-15 arrangements of patients with BCM. In addition, we have demonstrated that the Mollon-Reffin (MR) Minimal test is a useful colour-discrimination test to aid in the diagnosis of BCM. Affected males were shown to fail the protan and deutan axes, but retained good discrimination on the tritan axis of the MR test, a compelling evidence for residual colour vision in BCM. This residual tritan discrimination was also readily detected with HRR plates. In two families, psychophysical testing demonstrated evidence for progression of disease. In two pedigrees, BCM could be linked to unequal crossovers within the opsin gene array that resulted in a single 5'-L/M-3' hybrid gene, with an inactivating Cys203Arg mutation. The causative mutations were not identified in the third family. CONCLUSIONS: The MR test is a useful method of detecting BCM across a wide range of age groups; residual tritan colour discrimination is clearly demonstrated and allows BCM to be distinguished from rod monochromatism. BCM is usually classified as a stationary cone dysfunction syndrome; however, two of our families show evidence of progression. This is the first report of progression associated with a genotype consisting of a single 5'-L/M-3' hybrid gene carrying an inactivating mutation. We have confirmed that the Cys203Arg inactivating mutation is a common sequence change in blue cone monochromats.
AIM: To perform a detailed clinical and psychophysical assessment of the members of three British families affected with blue cone monochromatism (BCM), and to determine the molecular basis of disease in these families. METHODS: Affected and unaffected members of three families with BCM were examined clinically and underwent electrophysiological and detailed psychophysical testing. Blood samples were taken for DNA extraction. The strategy for molecular analysis was to amplify the coding regions of the long wavelength-sensitive (L) and middle wavelength-sensitive (M) cone opsin genes and the upstream locus control region by polymerase chain reaction, and to examine these fragments for mutations by direct sequencing. RESULTS: We have confirmed the reported finding of protan-like D-15 arrangements of patients with BCM. In addition, we have demonstrated that the Mollon-Reffin (MR) Minimal test is a useful colour-discrimination test to aid in the diagnosis of BCM. Affected males were shown to fail the protan and deutan axes, but retained good discrimination on the tritan axis of the MR test, a compelling evidence for residual colour vision in BCM. This residual tritan discrimination was also readily detected with HRR plates. In two families, psychophysical testing demonstrated evidence for progression of disease. In two pedigrees, BCM could be linked to unequal crossovers within the opsin gene array that resulted in a single 5'-L/M-3' hybrid gene, with an inactivating Cys203Arg mutation. The causative mutations were not identified in the third family. CONCLUSIONS: The MR test is a useful method of detecting BCM across a wide range of age groups; residual tritan colour discrimination is clearly demonstrated and allows BCM to be distinguished from rod monochromatism. BCM is usually classified as a stationary cone dysfunction syndrome; however, two of our families show evidence of progression. This is the first report of progression associated with a genotype consisting of a single 5'-L/M-3' hybrid gene carrying an inactivating mutation. We have confirmed that the Cys203Arg inactivating mutation is a common sequence change in blue cone monochromats.
Authors: Joseph Carroll; Alfredo Dubra; Jessica C Gardner; Liliana Mizrahi-Meissonnier; Robert F Cooper; Adam M Dubis; Rick Nordgren; Mohamed Genead; Thomas B Connor; Kimberly E Stepien; Dror Sharon; David M Hunt; Eyal Banin; Alison J Hardcastle; Anthony T Moore; David R Williams; Gerald Fishman; Jay Neitz; Maureen Neitz; Michel Michaelides Journal: Invest Ophthalmol Vis Sci Date: 2012-12-05 Impact factor: 4.799
Authors: Jessica C Gardner; Tom R Webb; Naheed Kanuga; Anthony G Robson; Graham E Holder; Andrew Stockman; Caterina Ripamonti; Neil D Ebenezer; Olufunmilola Ogun; Sophie Devery; Genevieve A Wright; Eamonn R Maher; Michael E Cheetham; Anthony T Moore; Michel Michaelides; Alison J Hardcastle Journal: Am J Hum Genet Date: 2010-06-24 Impact factor: 11.025
Authors: Joseph Carroll; Ethan A Rossi; Jason Porter; Jay Neitz; Austin Roorda; David R Williams; Maureen Neitz Journal: Vision Res Date: 2010-07-16 Impact factor: 1.886
Authors: Anne Moskowitz; Ronald M Hansen; James D Akula; Susan E Eklund; Anne B Fulton Journal: Invest Ophthalmol Vis Sci Date: 2008-09-29 Impact factor: 4.799
Authors: Jessica C Gardner; Michel Michaelides; Graham E Holder; Naheed Kanuga; Tom R Webb; John D Mollon; Anthony T Moore; Alison J Hardcastle Journal: Mol Vis Date: 2009-05-01 Impact factor: 2.367