The edge formed by the β2- and β7-strands is where one of the highly conserved arginine residues [8] locates: precisely, the one which when mutated in αB-crystallin (CRYAB, CTPP2, HSPB5; [9]) and αA-crystallin (CRYAA, CRYA1, HSPB4; [10]), causes cataract (R116C CRYAA and R120G CRYAB) and cardiomyopathy (R120G CRYAB). The gene discussed is CRYAB; the disease is cardiomyopathy.