LAUSR

Background Kearns–Sayre syndrome (KSS) is a rare, multisystem mitochondrial encephalomyopathy. We report a case of KSS with a novel 7.6-kb deletion as assessed through a long-range polymerase chain reaction (PCR) study in the blood. In addition, optical coherence tomography angiography (OCTA) confirmed deep retinal capillary atrophy for the first time. Case presentation A 13-year-old patient presented with progressive vision loss and difficulty with eye opening and was diagnosed with progressive external ophthalmoplegia and retinitis pigmentosa (RP). The patient also experienced heart block, vestibular dysfunction, growth retardation and multiple demyelinating lesions. A long-range PCR study in the blood revealed a large-scale Chrm: 6341–13,993 deletion, which was first reported and broadened the genetic spectrum of this disease. The patient underwent complete ophthalmic examination, medical history review and gene detection, resulting in a confirmation of the diagnosis of KSS. The patient was given a pair of applicable glasses to wear and was followed up every 3 months. An implantable pacemaker was also installed based on the advice of the physician. Conclusions We reported a novel large-scale deletion in the mitochondrial DNA of KSS, and OCTA was used for the first time to confirm deep retinal capillary atrophy. Furthermore, because ophthalmic symptoms are often the primary manifestation of KSS, the relationship between ophthalmology and mitochondrial diseases should be emphasised.