Since mutations in the CNGA3 gene may cause a variety of retinal dystrophies (complete and incomplete achromatopsia and progressive cone dystrophy), GNAT2 mutations may also prove to be implicated in other forms of retinal dystrophy with cone dysfunction.
Genetic testing revealed a common homozygous mutation in CNGB3 in 5 patients with complete achromatopsia and heterozygous mutations in CNGA3 in 2 patients with incomplete achromatopsia.
Genetic testing revealed a common homozygous mutation in CNGB3 in 5 patients with complete achromatopsia and heterozygous mutations in CNGA3 in 2 patients with incomplete achromatopsia.
However, a small number of patients carrying the CNGB3/c.1208G>A;p.R403Q mutation present with a variable retinal phenotype ranging from complete and incomplete achromatopsia to moderate cone dysfunction or progressive cone dystrophy.
Since mutations in the CNGA3 gene may cause a variety of retinal dystrophies (complete and incomplete achromatopsia and progressive cone dystrophy), GNAT2 mutations may also prove to be implicated in other forms of retinal dystrophy with cone dysfunction.
High-resolution X chromosome-targeted CGH microarray was applied to test for rearrangements in males with BCM and female carriers from three unrelated families.
Genetic analysis identified the presence of novel double heterozygous of c.361G>A; p.E121K in NR2E3, a gene responsible for enhanced S-cone syndrome (ESCS; OMIM #268100) and c.244A>G; p.K82E in OPN1LW, a gene responsible for blue cone monochromacy (BCM; OMIM#303700).
Human blue cone monochromacy (BCM) is characterized by functional loss of both L- and M-cone opsins due to mutations in the OPN1LW/OPN1MW gene cluster on the X chromosome.
The present report provides the clinical findings and the genetic basis underlying a sporadic BCM case which is caused by a de novo deletion within the OPN1LW/MW gene cluster originating from the mother's germline due to Alu-repeat mediated recombination.
BCM is caused by either mutations in the red (OPN1LW) and green (OPN1MW) cone photoreceptor opsin gene array or large deletions encompassing portions of the gene array and upstream regulatory sequences that would predict a lack of red or green opsin expression.
Genetic analysis identified the presence of novel double heterozygous of c.361G>A; p.E121K in NR2E3, a gene responsible for enhanced S-cone syndrome (ESCS; OMIM #268100) and c.244A>G; p.K82E in OPN1LW, a gene responsible for blue cone monochromacy (BCM; OMIM#303700).