Kearns-Sayre syndrome (KSS) is a rare mitochondrial DNA deletion syndrome defined as the presence of ophthalmoplegia, pigmentary retinopathy, onset less than age 20 years, and one of the following: cardiac conduction defects, cerebellar syndrome, or cerebrospinal fluid protein above 100 mg/dl. KSS may affect many organ systems causing endocrinopathies, encephalomyopathy, sensorineural hearing loss, and renal tubulopathy. Clinical presentation at diagnosis is quite heterogeneous and, usually, few organs are affected with progression to generalized disease early in adulthood. We present the case of a boy with KSS presenting at the age of 5 years with myopathy, Addison's disease, primary hypoparathyroidism, and Fanconi syndrome. The proper replacement treatment along with the administration of mitochondrial metabolism-improving agents had a brief ameliorating effect, but gradual severe multisystemic deterioration was inevitable over the next 5 years.
Conclusion: This report highlights the fact that in case of simultaneous presentation of polyendocrinopathies and renal disease early in childhood, KSS should be considered.