20歲，男性。

        雙側易疲勞性上瞼下垂1個月。

        查體發現，雙側不全上瞼下垂。向上凝視時加重 ，休息時改善。

        重症肌無力相關檢查陰性。

        CSF乳酸升高。線粒體基因組檢測顯示MT-APT6A基因homoplasmic T9176C突變，為Leigh綜合征致病基因突變。

        其發病機製作者認為：fatigable ptosis may be ascribed to the dysfunction at centrally located synapse between the nuclear complex of the third nerve and supranuclear pathways.