The present invention provides methods for treating autosomal dominant hypercholesterolemia (ADH). According to certain embodiments, the ADH is caused by or associated with a gain-of-function mutation (GOFm) in a gene encoding PCSK9. The present invention therefore includes methods comprising selecting a patient who carries a GOFm in one or both alleles of the PCSK9 gene, and administering to the patient a pharmaceutical composition comprising a PCSK9 inhibitor. In certain embodiments, the PCSK9 inhibitor is an anti-PCSK9 antibody such as the exemplary antibody referred to herein as mAb316P.