To the Editor: Moraes et al. (May 18 issue)1 report that 32 of 62 patients with progressive external ophthalmoplegia (including 15 of 18 patients with Kearns—Sayre syndrome) had demonstrable deletions of mitochondrial DNA and that the family histories of these patients were negative. The Kearns—Sayre syndrome is said to be sporadic1,2; however, it has been reported to occur in families in both an autosomal recessive3 and an autosomal dominant4,5 fashion. Genetic heterogeneity is probably involved. However, it would be useful for genetic-counseling purposes to know not only that there was no family history of the disease, but also the.
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