Assessment of the contribution of insulin-like growth factor I receptor 3174 G-->A polymorphism to the progression of advanced retinopathy of prematurity

Retinopathy of prematurity (ROP) is a leading cause of blindness in children with short gestational age and low birthweight. The condition can cause abnormal vessel development that can lead to retinal detachment and blindness. It has been recently reported that a low level of insulin-like growth factor I (IGF-I) is associated with ROP. However, the most prevalent polymorphism of IGF-I receptor (IGF-IR 3174 G-->A) that was reported to be producing low level of IGF-I was not found to be associated with ROP in a certain population. In order to reproduce this data in a different cohort and to learn more about the contribution of IGF-IR polymorphism to ROP, the authors hypothesized that it is possible that such a polymorphism would occur more frequently in a different cohort of infants with advanced ROP than those children with mild or no disease. For genetic analysis, eligible patients were selected consecutively by experienced pediatric ophthalmologists and leukocyte DNA from affected (n=52) and normal patients (n=33) were amplified by polymerase chain reaction. The amplified products were subjected to restriction enzyme digestion with 10 units of MnlI enzyme. The digested products were analyzed by polyacrylamide gel electrophoresis followed by ethidium bromide staining to visualize the restriction fragment length polymorphism. The analysis suggests that there is no statistically significant difference in allelic frequency of the most prevalent IGF-IR gene polymorphism between normal subjects and patients with ROP in this cohort. The G-->A polymorphism did not occur more frequently in patients with ROP. The results do not support the association of the most prevalent IGF-IR gene polymorphism and the risk of advanced ROP in a different cohort, confirming the earlier report.