This spontaneous C to T transition in exon 2 of Gnat2 causes a change in codon 24 from CAG, glutamine, to TAG, a stop codon. Homozygotes develop a loss of cone-mediated response evident by electroretinography by 3 weeks of age, but the rod-mediated responses are normal. Even at 6 months of age the retina appears normal by histology. This mutation was further proven to be a defect in Gnat2 by failure to complement the Gnat2cpfl3 allele in an allele test. This mutation provides a model for autosomal recessive achromatopsia (ACHM4).
The Gnat2cpfl3-2J mutation arose spontaneously and was identified in the B10.129S2(B6)-Il3tm1Tyb/J strain by Dr. Bo Chang who backcrossed this phenotypic mutation onto C57BL/6J for five generations before sibling intercrossing to generate this strain devoid of the Il3tm1Tyb allele and homozygous for Gnat2cpfl3-2J. This strain reached generation N5F8 in 2021.
|Allele Name||cone photoreceptor function loss 3, 2 Jackson|
|Allele Type||Spontaneous (Not Specified)|
|Gene Symbol and Name||Gnat2, guanine nucleotide binding protein, alpha transducing 2|
|Strain of Origin||B10.129S2(B6)-Il3tm1Tyb/J|
|Molecular Note||a spontaneous single base pair change C to T in exon 2 results in a change at codon 24 from CAG to a TAG stop codon.|