[Molecular genetic findings in patients with congenital cone dysfunction. Mutations in the CNGA3, CNGB3, or GNAT2 genes].
OBJECTIVE
This study compares clinical and molecular genetic findings in patients with congenital cone dysfunction.


METHODS
In this study 28 patients underwent a basic ophthalmologic examination. Except for a 1-year-old boy, color vision, perimetry, and full-field ERG (ISCEV standard) were evaluated in all patients. Blood samples were taken for molecular genetic analysis of the CNGA3, CNGB3, or GNAT2 genes.


RESULTS
Two patient groups could be distinguished: patients without and with residual cone function in the ERG. In 14 of 17 patients without cone function, mutations in one of the three genes were detected, and except for one patient mutations in both alleles could be determined. In these patients, visual acuity was reduced to 20/400 and color discrimination was absent. In 2 of 11 patients with residual cone function, mutations in one allele of the CNGB3 gene were detected. It is of interest that 6 of 16 patients with mutations perceived their disease as progressive; in three of them we could determine a progression. Only in 4 of 16 patients was the ocular fundus normal. The other patients with mutations presented with central pigment irregularities, attenuated vessels, or pale optic disk.


CONCLUSIONS
In patients with congenital cone dysfunction without cone function in the ERG, an analysis of the CNGA3, CNGB3, or GNAT2 gene is advisable. In contrast, patients with residual cone function did not show clear association with mutations in one of the three genes. In patients with mutations, retinal alterations and nystagmus are frequent. In contrast to the designation of these disorders as stationary, in some patients with mutations in the CNGA3 and CNGB3 gene slow progression was observed.
Augenklinik Campus Benjamin Franklin, Charité Universitätsmedizin, Berlin. kellneru@retinascience.de
U
U
Kellner
B
B
Wissinger
S
S
Kohl
H
H
Kraus
M H
MH
Foerster
D000293:Adolescent; D000328:Adult; D002648:Child; D003119:Color Perception Tests; D003117:Color Vision Defects / Q000151:congenital / Q000175:diagnosis* / Q000235:genetics*; D054815:Cyclic Nucleotide-Gated Cation Channels; D004596:Electroretinography; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing / Q000379:methods; D006801:Humans; D007223:Infant; D007473:Ion Channels / Q000172:deficiency / Q000235:genetics*; D008297:Male; D009154:Mutation; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism*; D013223:Statistics as Topic; D015293:Transducin / Q000172:deficiency / Q000235:genetics*; D058609:Visual Field Tests
C415904:CNGB3 protein, human; D054815:Cyclic Nucleotide-Gated Cation Channels; D007473:Ion Channels; D015293:Transducin