ABCA4 and age-related macular degeneration: –24 The lack of association between p.Asn1868Ile and retinal thickness for these layers suggests that it may not be an AMD risk factor, and this is consistent with AMD genome-wide association analyses that do not identify any association at ABCA4.25,26 It is important to consider that the studies supporting an association between p.Asn1868Ile were conducted with small sample sizes (212 and 54 participants, respectively),19,20 whereas this study and the AMD genome-wide association analysis (GWAS) analyses had sample sizes in the tens of thousands.