Rod photoreceptor responses in children with Smith-Lemli-Opitz syndrome.
OBJECTIVE
To test the hypothesis that the kinetics of activation and deactivation of rod phototransduction are altered in children with Smith-Lemli-Optiz syndrome (SLOS), a common genetic disorder caused by an inborn error in cholesterol biosynthesis.


METHODS
Thirteen patients with SLOS (median age, 4 years) were studied by means of scotopic full-field electroretinography. The kinetics of activation and deactivation of rod phototransduction were derived from the electroretinographic a-wave. Postreceptoral electroretinographic components were also evaluated.


RESULTS
The kinetics of activation were below normal limits in all but 3 of the 13 patients. Rod cell recovery (deactivation) in SLOS was slower than normal in all 8 patients in whom it was studied. Postreceptoral sensitivity was below normal limits in all but 1 of the 13 patients.


CONCLUSIONS
The kinetics of phototransduction are slow in children with SLOS. This is likely a consequence of altered sterol composition in the cell membranes of the rod photoreceptors. To our knowledge, this is the first demonstration of altered kinetics of a membrane-bound signaling system in SLOS. Investigation of other membrane-bound signaling systems may be warranted in the quest to understand development and phenotype of individuals with SLOS.
Elias
Ellen R
ER
Departments of Ophthalmology and Medicine, Children's Hospital, New England College of Optometry, Boston, Massachusetts, USA.
Hansen
Ronald M
RM
Irons
Mira
M
Quinn
Nicole B
NB
Fulton
Anne B
AB
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004596:Electroretinography; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D012164:Retinal Diseases / Q000503:physiopathology*; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D019082:Smith-Lemli-Opitz Syndrome / Q000503:physiopathology*; D014785:Vision, Ocular / Q000502:physiology*