In preterm infants who did not develop ROP, carriers of both the NGF (GG) and BDNF (allele G) polymorphisms, as well as carriers of the NGF (GG), BDNF (allele G), and TH (allele C) polymorphisms, had significantly and independently lower percentages of immature granulocytes compared to carriers of other genotypes of the same genes (Table 8 and Table 10). The gene discussed is TH; the disease is retinopathy of prematurity.