Thelansis

Blue cone monochromatism (BCM) is a rare X-linked congenital cone dysfunction syndrome, caused by mutations in the OPN1LW/OPN1MW gene cluster on the X chromosome. The cluster contains a single OPN1LW and one or more copies of the OPN1MW gene and controls the expression of the red (L, long wavelength) and green (M, middle wavelength) cone photoreceptor opsins. The genes expressing the opsin for the third cone subtype, S (short-wavelength) or blue cones (OPN1SW), and the rod pigment are autosomal and not affected in BCM. Consequently, vision in affected males is subserved only by S cone and rod function, as no functional L or M cones are present in the retina while Tritan discrimination, which has been reported to deteriorate with increasing illuminance and scotopic perception are retained. ·        The prevalence of Blue cone monochromatism (BCM) varies between 1 to 1.75 cases per 100,000 population. Colour discrimination is severely impaired from birth and ...

 Blue cone monochromatism (BCM) is a rare X-linked congenital cone dysfunction syndrome, caused by mutations in the OPN1LW/OPN1MW gene cluster on the X chromosome. The cluster contains a single OPN1LW and one or more copies of the OPN1MW gene and controls the expression of the red (L, long wavelength) and green (M, middle wavelength) cone photoreceptor opsins. The genes expressing the opsin for the third cone subtype, S (short-wavelength) or blue cones (OPN1SW), and the rod pigment are autosomal and not affected in BCM. Consequently, vision in affected males is subserved only by S cone and rod function, as no functional L or M cones are present in the retina while Tritan discrimination, which has been reported to deteriorate with increasing illuminance and scotopic perception are retained. ·        The prevalence of Blue cone monochromatism (BCM) varies between 1 to 1.75 cases per 100,000 population. Colour discrimination is severely impaired from bi...

  Blue cone monochromatism (BCM) is a rare X-linked congenital cone dysfunction syndrome, caused by mutations in the OPN1LW/OPN1MW gene cluster on the X chromosome. The cluster contains a single OPN1LW and one or more copies of the OPN1MW gene and controls the expression of the red (L, long wavelength) and green (M, middle wavelength) cone photoreceptor opsins. The genes expressing the opsin for the third cone subtype, S (short-wavelength) or blue cones (OPN1SW), and the rod pigment are autosomal and not affected in BCM. Consequently, vision in affected males is subserved only by S cone and rod function, as no functional L or M cones are present in the retina while Tritan discrimination, which has been reported to deteriorate with increasing illuminance and scotopic perception are retained. The prevalence of Blue cone monochromatism (BCM) varies between 1 to 1.75 cases per 100,000 population. Colour discrimination is severely impaired from birth and BCM patients typically present...