3.1-kb deletion of mitochondrial DNA in a patient with Kearns-Sayre syndrome.

Mitochondrial DNA (mtDNA) deletions have been found in the majority of patients with chronic progressive external ophthalmoplegia and Kearns-Sayre syndrome. A large number of different mtDNA deletions have been identified. They generally spare the two origins of replication and are frequently flanked by direct or indirect repeats. We have found a 3.1-kb deletion of mtDNA in a patient with Kearns-Sayre syndrome that has some unusual features. First, it encompasses nucleotides 11259 to 14368, a localization that was not described before. Second, the deletion is not flanked by direct or indirect repeats, supporting the view that homologous recombination and slip-replication do not account for all mtDNA deletions.

The occurrence of beta-glucuronidase in erythrocyte inclusions.

This study presents erythrocytic inclusion bodies exhibiting histochemically a strong beta-glucuronidase activity. The unique occurrence of this enzyme in cells of the erythropoietic series has never been described before and characterizes a novel type of erythrocyte inclusions mainly observed in patients suffering from liver damage but also from myelodysplasia and congenital dyserythropoietic anemia type I. Since it is known that hepatocytes contain high activities of beta-glucuronidase, we supposed a relationship between an increased breakdown of liver cells and the appearance of beta-glucuronidase positive inclusions in the red cells. To prove this hypothesis, we determined the beta-glucuronidase plasma levels of 99 unselected patients suffering from various liver disorders in comparison with 19 healthy controls by use of the umbelliferone technique. Our results indicate that in cases with liver diseases beta-glucuronidase plasma levels are significantly increased as compared with normal persons. The availability of a sufficient amount of beta-glucuronidase, thus, seems to be one prerequisite for the appearance of these inclusions in erythrocytes. As demonstrated by our investigations on congenital dyserythropoietic anemia, in which the red cells also show beta-glucuronidase positive inclusions, another premise seems to be an elevated autophagolysosomal activity in the erythrocytes.