The values of histopathological score were: CO: 0.49 ± 0.14; AT: 12.44 ± 1.29 (p < 0.001 AT vs CO); and AT+IGF: 7.78 ± 1.38 (p < 0.001 vs CO and p < 0.01 vs AT), demonstrating severe testicular damage in untreated AT rats and a significant improvement in AT rats treated with IGF-I. The gene discussed is IGF1; the disease is ataxia telangiectasia.