Defective OPN1LW causes BCM

Stable Identifier
Reaction [transition]
Homo sapiens
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Normal human colour vision is trichromatic, based on 3 types of cones that are maximally sensitive to light at approximately 420 nm (blue cones), 530 nm (green cones), and 560 nm (red cones). Neural circuits compare light absorbed by these 3 cone types to perceive those primary colours and combinations of them. Colour vision deficiencies result from genetic mutations that affect the expression of the full complement of cone photoreceptors and are classified by severity of deficiency.

Anomolous trichromacy is the mildest form. Although affected individuals express all three cones, the way the cones process the primary colours is aberrant so discriminating various colours is difficult. Anomolous trichromacy is subdivided into protanomaly (affects red cones), deuteranomaly (affects green cones) and tritanomaly (affects blue cones). Dichromacy is the next severest colour vision deficiency. Dichromats have reduced colour vision based on the use of only 2 types of cone photoreceptors. Dichromacy is subdivided into protanopia (no functional red cones), deuteranopia (no functional green cones) and tritanopia (no functional blue cones). Monochromacy is the severest form of colour vision deficiency in which colour discrimination is absent due to dysfunctional or non-functional cones. All vision is therefore mediated by rods which otherwise usually function only in night conditions (see reviews Deeb 2005, Simunovic 2010).

Blue cone monochromatism (BCM) is a rare X-linked congenital cone dysfunction characterized by the absence of functional long wavelength-sensitive (red) and medium wavelength-sensitive (green) cones in the retina. Colour discrimination is severely impaired from birth, and vision is derived from the preserved short wavelength-sensitive (blue) cones and rod photoreceptors. BCM typically presents with reduced visual acuity, pendular nystagmus, photophobia and patients often have myopia. BCM affects approximately 1 in 100,000 individuals (see review Gardner et al. 2009). The mutation C203R causes non-functional green and red cones by misfolding and retention of the protein in the endoplasmic reticulum. Two other mutation that abolish function of OPN1LW like C203R are R247* and P307L (Nathans et al. 1989, Nathans et al. 1993, Reyniers et al. 1995).

Literature References
PubMed ID Title Journal Year
8213841 Genetic heterogeneity among blue-cone monochromats

Sadowski, B, Zrenner, E, Maumenee, IH, Nathans, J, Schwartz, M, Lewis, RA, Heckenlively, JR, Rosenberg, T, Hansen, E, Sharpe, LT

Am. J. Hum. Genet. 1993
12051694 Novel missense mutations in red/green opsin genes in congenital color-vision deficiencies

Wada, A, Nishida, Y, Tanabe, S, Kuwayama, S, Yamade, S, Ueyama, H, Shichida, Y, Oda, S, Imai, H

Biochem. Biophys. Res. Commun. 2002
8666378 Gene conversion between red and defective green opsin gene in blue cone monochromacy

Van Thienen, MN, Kestelijn, P, Willems, PJ, Devries, K, De Boulle, K, Reyniers, E, Meire, F

Genomics 1995
2788922 Molecular genetics of human blue cone monochromacy

Lovrien, E, Litt, M, Bachynski, B, Hejtmancik, JF, Maumenee, IH, Zwas, F, Nathans, J, Lewis, RA, Davenport, CM, Weleber, R

Science 1989
Normal reaction
Functional status

Loss of function of OPN1LW mutants [photoreceptor disc membrane]

Name Identifier Synonyms
blue cone monochromacy DOID:0050679 blue cone monochromatism
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