The
Kearns-Sayre syndrome, (characterized by its onset before the age of 20 years, chronic
ophthalmoplegia, pigmentary
retinal degeneration and at least one of the following symptoms:
ataxia,
heart block and high
protein content in the cerebrospinal fluid) is a severe variant of
chronic progressive external ophthalmoplegia with frequent rearrangements of the
mitochondrial DNA (
mtDNA). The aim of this paper is to report a sporadic paediatric case of
Kearns-Sayre syndrome with
mtDNA heteroplasmic deletion, absence of
cytochrome c-oxidase in many muscle fibers,
autoimmune thyroiditis, complete atrio-ventricular
heart block in which the diagnosis of subclinical hypothyroiditis associated with autoimmune
thyroid disease was made. The subclinical
hypothyroidism, more severe in the presence of thyroid
antibodies, may have contributed to the pathogenesis of
cardiovascular disease. We hypothesized that in this patient, predisposed by mitochondrial deletion, anti-thyroid
antibodies may have interfered with the mitochondrial function of conduction heart system, causing atrio-ventricular
heart block. It seems important to study anti-thyroid
antibodies in every case of Kearn-Sayre syndrome, specially if cardiac rhythm disturbances are present.