Gnat2cpfl3 homozyogtes have poor cone-mediated responses evident by 3 weeks of age and completely lack cone-mediated responses from 9 weeks of age on. This strain provides a model for achromatopsia 4.Read More +
On this C57BL/6J congenic background this spontaneous mutation in Gnat2 causes homozygotes to have an abnormal light-adapted electroretinogram as early as 3 weeks of age, the earliest timepoint assessed. Fundus photographs are normal and no abnormalities are detected in retinal structure by 6 months of age in optical coherence tomography and histology.
On the ALS/LtJ background, electroretinography shows that cpfl3 homozyogtes have poor cone-mediated responses evident by 3 week of age and completely lack cone-mediated responses from 9 weeks of age on. Rod-mediated responses are nearly normal, but with some diminution with age. Histology shows the normal 8 to 10 rows of rod nuclei at 6 and 15 weeks of age, but vacuolization and shortening of the photoreceptor outer segments is found at 27 weeks of age. Loss of immunohistochemical staining of cone-specific alpha transducin occurs by 4 weeks of age yet peanut agglutinin staining shows a normal number of cone outer segments at 14 weeks of age. Fundus photographs are essentially normal except for slightly dilated retinal veins and slightly contracted arterioles at 8 months of age.
The Gnat2cpfl3 allele was backcrossed from ALS/LtJ onto C57BL/6J in the laboratory of Dr. Bo Chang at The Jackson Laboratory and subsequently bred to homozygosity. The mutation consists of a single nucleotide substitution of G to A at position 598 in exon 6. This mutation converts codon 200 from aspartic acid to asparagine.
|Allele Name||cone photoreceptor function loss 3|
|Allele Synonym(s)||no cones|
|Gene Symbol and Name||Gnat2, guanine nucleotide binding protein, alpha transducing 2|
|Strain of Origin||various|
|General Note||This allele has been detected in the following strains either by genotyping or complementation testing: ALS/LtJ, SENCARA/PtJ, SENCARB/PtJ, SENCARC/PtJ, PN/nBSwUmabJ. (J:122428) The allele has also been reported in NMRI and CD1 (Lluis Montoliu, J:212307)|
|Molecular Note||A single nucleotide substitution of G to A at coding nucleotide 598 in exon 6. This mutation converts codon 200 from aspartic acid to asparagine (p.D200N).|