A PCR test for progressive external ophthalmoplegia and Kearns-Sayre syndrome on DNA from blood samples

Progressive external ophthalmoplegia (PEO) and Kearns-Sayre syndrome (KSS) are caused by deletions in mitochondrial DNA. Identification of these deletions is important for diagnosis, prognosis and genetic counselling. As yet, the most frequently used test is Southern blot analysis of DNA isolated from a muscle biopsy. Here, we describe a sensitive PCR-based test for the identification of these deletions in DNA isolated from blood. The main advantage is that in the majority of cases a muscle biopsy is no longer necessary for the molecular diagnosis of PEO and KSS.