To date, no GWAS has been published for ROP; case control and whole exome candidate gene approaches have reported significant risk associations between single nucleotide polymorphisms (SNP) in brain-derived neurotrophic factor (BDNF; rs7934165 and rs2049046), thrombospondin type-1 domain-containing protein 4 (THSD4), TNF -308G/A polymorphism and angiotensin 1 converting enzyme insertion deletion (ACE ID) polymorphism8,16–18 (Supplementary Table 1). The gene discussed is THSD4; the disease is retinopathy of prematurity.