No abstract

Survival, decrease of the diastolic thickness of the left ventricular posterior wall, and achievement of major motor milestones are valid endpoints for therapeutic studies of infantile Pompe's disease. Mutation analysis and measurement of the alpha-glucosidase activity should be part of the enrollment program.

Late-onset Pompe's disease (acid maltase deficiency, glycogen storage disease type II) is a slowly progressive myopathy caused by deficiency of acid alpha-glucosidase. Current developments in enzyme replacement therapy require detailed knowledge of the kind and severity of symptoms and the natural course of the disease in the patient population. A detailed questionnaire covering the patients' medical history and current situation was developed and information was gathered from 54 Dutch patients. The mean age of the participants was 48.6 +/- 15.6 years. The first complaints started at a mean age of 28.1 +/- 14.3 years and were mostly related to mobility problems and limb-girdle weakness. Fifty-eight percent of the adult patients indicated the presence of mild muscular symptoms during childhood. Twenty-eight percent of the patients waited >5 years for the final diagnosis after the first visit to a physician for disease-related complaints. At the time of questionnaire completion, 48% of the study population used a wheelchair and 37% used artificial ventilation. Movements such as rising from an armchair, taking stairs or getting upright after bending over were difficult or impossible for more than two-thirds of the respondents. The age at onset, the rate of disease progression and the sequence of respiratory and skeletal muscle involvement varied substantially between patients. Seventy-six percent of the participants indicated being troubled by fatigue and 46% by pain. This survey has mapped the age at onset, presenting symptoms, heterogeneity in progression and range of disease severity in a large group of Dutch patients. We conclude that early manifestations in childhood require proper attention to prevent unnecessary delay of the diagnosis. The follow-up of patients with late-onset Pompe's disease should focus on respiratory and limb-girdle muscle function, the capacity to perform daily activities, and the presentation of fatigue and pain.

Tuberous sclerosis (TSC) is an autosomal dominant disorder caused by a mutation in either the TSC1 or TSC2 tumour suppressor gene. The disease is characterized by a broad phenotypic spectrum that can include seizures, mental retardation, renal dysfunction and dermatological abnormalities. TSC2 encodes tuberin, a putative GTPase activating protein for rap1 and rab5. The TSC1 gene was recently identified and codes for hamartin, a novel protein with no significant homology to tuberin or any other known vertebrate protein. Here, we show that hamartin and tuberin associate physically in vivo and that the interaction is mediated by predicted coiled-coil domains. Our data suggest that hamartin and tuberin function in the same complex rather than in separate pathways.

Pompe's disease is a neuromuscular disorder caused by deficiency of lysosomal acid alpha-glucosidase. Recombinant human alpha- glucosidase is under evaluation as therapeutic drug. In light of this development we studied the natural course of cases not fitting the definition of classic infantile Pompe's disease. Our review of 109 reports including 225 cases shows a continuous spectrum of phenotypes. The onset of symptoms ranged from 0 to 71 years. Based on the available literature, no criteria to delineate clinical sub-types could be established.A common denominator of these cases is that first symptoms were related to or caused by muscle weakness. In general, patients with a later onset of symptoms seemed to have a better prognosis. Respiratory failure was the most frequent cause of death. CK, LDH, ASAT, ALAT and muscle glycogen levels were frequently but not always elevated. In most cases a muscle biopsy revealed lysosomal pathology, but normal muscle morphology does not exclude Pompe's disease. In 10% of the cases in which the enzyme assay on leukocytes was used, a normal alpha-glucosidase activity was reported. Data on skeletal muscle strength and function, pulmonary function, disability, handicap and quality of life were insufficiently reported in the literature. Studies of non-classic Pompe's disease should focus on these aspects, before enzyme replacement therapy becomes generally available.