Purpose:
To describe the clinical features, and DNA mitochondrial diagnosis in a patient with Kearns–Sayre syndrome.
Methods:
A 15 year–old female presented to us with a 2–year history of ptosis and limitation of movement in both eyes. She had no previous history of diabetes, hypertension or trauma. On ophthalmic examination her visual acuity was 20/40(.)20/30 OD, and 20/25(.)20/25 OS with an intraocular pressure of 11 mmHg OD and 12 mmHg OS. The examination of ocular motility showed marked limitation in all directions of gaze for both eyes. The prism cover test showed 15 prism diopters of exotropia at near and far distances. For both eyes, on the ptosis study, the interpalpebral fissure was 7.0mm, with a levator function 5.0mm, and a margin reflex distance of 1.0mm. The pupil size was within normal limits and direct pupil light reflex was intact. The anterior segments of both eyes were within normal limits. During funduscopic examination multiple pigmentary changes (salt and pepper–like appearance) were noted on the entire peripheral fundus in both eyes. Fluorescein angiography showed moderate retinal pigment atrophy in the peripheral fundus. Electroretinography was abnormal for all stimuli. Kinesiologic electromyography study showed affection of extraocular muscles, frontal muscle and pharynx. Electrocardiogram showed right bundle branch block. Mitochondrial DNA was obtained from platelets using a polymerase chain reaction strategy to amplify a 5kb product because the Kearns–Sayre syndrome deletion amplifies 349bp long.
Results:
In this patient we found amplification of a band in 349bp that indicates a common deletion in 4977bp for Kearns–Sayre syndrome. In contrast, no deletion in DNAm was found in our control subject.
Conclusions:
Nested PCR strategy helped to confirm the diagnosis of Kearns–Sayre syndrome in this patient. PCR is a quick and cheap method for the diagnosis of a common deletion in Kearns–Sayre syndrome, in these type of cases PCR could avoid other methods such as muscular biopsies or lumbar punctures.
Keywords: genetics • neuro-ophthalmology: diagnosis • eye movements