HTRA1 and age-related macular degeneration: ,14 Thus, Schmitz-Valckenberg et al. showed that patients with AMD homozygous for AMD-risk variants in the ARMS2/HTRA1 locus with or without additional risk variants in the CFH-CFHR5 locus had a higher risk for progression to late AMD as compared with AMD subjects homozygous for risk variants at CHF-CFHR5 only.13