KSS

Kearns-Sayre Syndrome

Clinical Characteristics

Ocular Features:

Ptosis and progressive ophthalmoplegia usually have their onset before the second decade of life. Pigmentary retinopathy is common with a variable clinical pattern of simple salt-and-pepper pigmentation or pigmentary clumping resembling retinitis pigmentosa.

Systemic Features:

Atrioventricular conduction defects including complete heart block, cardiomyopathy, short stature, elevated CSF protein, and ataxia are among the most frequent extraocular features seen. Pharyngeal, facial, and skeletal muscle weakness seem to be common features. Growth retardation, delayed sexual maturation, and mental deterioration occur in some patients. Older patients have a sensorineural hearing deficit as well.

EEG abnormalities are often present. CT scans reveals a diffuse leukoencephalopathy as well as a variety of CNS abnormalities in the cerebellum and brain stem. Muscle biopsies reveal 'ragged red' fibers.

This is a progressive disorder and many patients die in the third or fourth decades of life.

Genetics

Unlike many syndromes of external ophthalmoplegia with deletions in mitochondria, no nuclear DNA mutations have been associated with this disorder. However, it is a clinically and genetically heterogeneous condition. Exclusively maternal transmission consistent with mitochondrial disease has been observed in some familial cases. Other familial cases suggest autosomal inheritance and in some the transmission pattern is consistent with autosomal recessive inheritance. Many if not most cases occur sporadically.

Mitochondrial DNA defects in muscle and brain vary in size and location and even the proportion of normal to abnormal mitochondria among cells varies. This may account for some of the clinical heterogeneity.

Treatment

Treatment Options:

Coenzyme Q(10) may decrease fatigue with improvement in eye muscle movement and a lessening in the degree of heart block. Pacemakers may be necessary in some patients. Exercise is recommended for patients with significant skeletal myopathy.

References

Article Title:

Kearns-Sayre syndrome is genetically and phenotypically heterogeneous

Finsterer J, Zarrouk-Mahjoub S. Kearns-Sayre syndrome is genetically and phenotypically heterogeneous. Pediatr Med Chir. 2018 May 29;40(1). doi: 10.4081/pmc.2018.193.

PubMed ID:

29871478

Kearns-Sayre syndrome: a case series of 35 adults and children

Khambatta S, Nguyen DL, Beckman TJ, Wittich CM. Kearns-Sayre syndrome: a case series of 35 adults and children. Int J Gen Med. 2014 Jul 3;7:325-32. eCollection 2014.

PubMed ID:

25061332

Mitochondrial DNA deletions in progressive external ophthalmoplegia and Kearns-Sayre syndrome

Moraes CT, DiMauro S, Zeviani M, Lombes A, Shanske S, Miranda AF, Nakase H, Bonilla E, Werneck LC, Servidei S, et al. Mitochondrial DNA deletions in progressive external ophthalmoplegia and Kearns-Sayre syndrome. N Engl J Med. 1989 May 18;320(20):1293-9.

PubMed ID:

2541333

Genotype and phenotype analyses in 136 patients with single large-scale mitochondrial DNA deletions

Yamashita S, Nishino I, Nonaka I, Goto Y. Genotype and phenotype analyses in 136 patients with single large-scale mitochondrial DNA deletions. J Hum Genet. 2008;53(7):598-606.

PubMed ID:

18414780

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