Supplementary Material for: Case Report: Endocrine manifestations in Kearns-Sayre syndrome

Introduction: Kearns–Sayre syndrome [KSS] is a rare disorder caused by mutations in mitochondrial DNA. Some patients with mitochondrial diseases exhibit endocrine manifestations, the most frequent of which diabetes mellitus.
Case Presentation: We report a case of a 20-year-old male, who initially presented with growth failure. At age 11 years, he experienced progressive vision loss, bilateral ptosis and ophthalmoplegia, cerebellar ataxia, delays in fine motor skills, dysmetria, fatigue and exercise intolerance. Initial medical work-up demonstrated elevated protein levels in the cerebrospinal fluid, cone-rod dystrophy, delayed bone age and low insulin-like growth factor-1. Enhanced cerebral magnetic resonance imaging revealed abnormal findings in the cerebellar white matter and mesencephalon. A third-degree atrioventricular block led to the need for a pacemaker placement. Subsequently, the patient was diagnosed with secondary hypothyroidism and hypogonadism. Polymerase chain reaction [PCR] sequencing revealed a large-scale mitochondrial DNA deletion. Hormone replacement therapy was initiated for endocrinopathies. However, his growth did not improve after recombinant human growth hormone treatment.
Conclusion: Endocrine manifestations are frequent and can be the first signs of KSS. However, this case emphasizes that KSS may present with growth failure years before other manifestations of the disease and underscores the rare coexistence of Kearns–Sayre syndrome and hypopituitarism. Maintaining a high level of suspicion is crucial for achieving an accurate and timely diagnosis, and a multidisciplinary follow-up is essential for the better management of these patients.