INTRODUCTIONAnatomical investigations OIL PI ogrossivo myoclonus epilepsy have so far been focussed mainly on the nervous system. Harriman and Millar (13) and Seitelberger (30) however, called attention to the presence of PAS-positive deposits in the liver and the myocardium in a patient with progressive myoclonus epilepsy and with Lafora bodies in the nervous system. In a subsequent paper Millar and Neil1 (22) presented a preliminary report on changes in the mucoprotein fraction of the serum in affected and in non-affected siblings in families with myoclonus epilepsy, described in Harriman and Millar's paper. These data, and the familial occurrence of progressive myoclonus epilepsy, suggest that we are dealing with an inborn error of metabolism, which, among others or perhaps mainly, affects the nervous system.The present paper demonstrates the presence of "storage cells" in the brain in the two cases of progressive myoclonus epilepsy described by van Heycop ten Ham et al. (15) and in a 4-day-old nephew of these patients. In addition, preliminary information is provided on the probable accumulation of carbohydrates and/or carbohydrate complexes in the liver and the heart of one of these patients. The result of morphological and biochemical studies will first be treated separately and then discussed together.
MORPHOLOGY
NeuropathologyIn addition to the complete nervous system of patients 26 and 28 reported on by van Heycop ten Ham et al. (15), a small paraffin-embedded block from the brainstem of a 4-day-old nephew of these patients was also available*.The delivery of this first child was normal; no abnormalities were noticed in the first two days, but then convulsions appeared and the child died on the fourth day of life. At autopsy there were several haemorrhages in the lungs and oedema of the * We like to express our thanks to Dr. P. M. Bakker, Municipal Hospital, The Hague (The Netherlands), who kindly supplied this material.