A process of detecting the presence of or susceptibility to a disease involving the Frizzled-4 receptor is provided. The inventive method determines the presence or absence of one or more mutations in Frizzled-4 alone or in conjunction with other proteins such as Norrin and LRP5. The presence of a mutation predicts the presence of a disease or susceptibility to a disease. The inventive process further provides correction or prevention of a disease by administration of frizzled-4 to a subject to alter or maintain a physiological function.
