Glycogenosis type VII. Tauri disease. Phosphofructokinase deficiency.
Incidence
Rare disease. AR inheritance. Glycolysis is impaired. Recent molecular studies have demonstrated that a particular splicing mutation (exon 5 deletion) is present in more than 50% of Ashkenazi-Jewish patients with PFK deficiency.
Clinical Characteristics
It usually presents with cramps on exercise and myoglobinuria. In addition to muscle symptoms, some pts. may have bouts of hemolysis. A neonatal form has been reported charact. by hypotonia, weakness, respiratory insufficiency & joint deformities. In this neonatal form, cerebral involvement is present, and death supervenes during the first year. In the usual form, motor development is normal during the first decade, but pts. have decreased exercise tolerance during childhood.
Precipitants
Exercise trigger crisis and muscle pain with myoglobinuria.
Provocation Tests
Ischaemic exercise test: Lactate should increase higher than 2 mmol/L with exercise normally. In this condition, there is no increase of lactate, and cramps may appear during the test, like in McArdle disease.
Diagnostic Procedures
EB-muscle, EB-RBC. Mutations have been identified in this condition. These can now be detected in DNA isolated from the blood. This analysis provides a practical alternative to muscle biopsy for initial screening.