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One of the four glycogen storage diseases
characterized by phosphofructokinase deficiency in the muscles and
associated with abnormal deposition of glycogen in muscle tissues, exercise
intolerance, and anemia.
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Muscle Phosphofructokinase Deficiency; Tarui Disease;
Glycogenosis type VII.
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Also named Tarui disease after the Japanese physician Seiichiro
Tarui (born in 1927) who first described the disease in 1965.
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Less than 50 cases reported (<10 for the infantile
lethal form). This condition is mainly observed in the Ashkenazi Jewish
people.
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Autosomal recessive; however, more males than
females have been reported. The gene causing GSD VII (M subunit gene) has
been mapped to chromosome 1.
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Deficiency of muscle phosphofructokinase, which
catalyzes the irreversible conversion of fructose-6-phosphate to
fructose-1,6-bisphosphate in glycolysis. As a consequence, free or
glycogen-derived glucose cannot be used as a source of energy and glycogen
accumulates because of impaired degradation and/or excess synthesis.
Increased levels of glucose-6-phosphate activate the hexose monophosphate
shunt, thus enhancing nucleotide formation and uric acid production. The
enzymatic block also causes a decrease in 2,3-diphosphoglycerate (DPG).
Oxygen affinity of hemoglobin is therefore increased, as is the production of new
erythrocytes, resulting in compensated anemia.
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Based on the clinical findings in patients with muscular exercise
intolerance exacerbated by glucose infusion prior to exercise, fatigue,
vomiting, muscle weakness, myalgia, cramps, and myoglobinuria.
Phosphofructokinase deficient in skeletal muscle, but not in the liver. No
rise in blood lactate concentration after ischemic exercise. Plasma creatine phosphokinase
is increased. 31P-NMR
spectroscopy reveals a specific peak of phosphorylated monoesters
(accumulation of glycolytic intermediates resulting from the enzymatic
block). A severe infantile form with arthrogryposis, cardiomyopathy, and frequent
respiratory failure has been described. Death occurs early. Antenatal detection
possible in families with identifiable mutations.
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Clinical features similar to GSD type V.
Temporary weakness and painful muscle cramps occur after exercise.
Myoglobinuria may occur with extreme exertion. Patients tend to develop
hemolytic anemia (with jaundice as a result of partial erythrocyte
phosphofructokinase deficiency) and myogenic hyperuricemia.
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Three clinical forms have been described: classic, infantile onset, and late
onset type. The classic form includes exercise intolerance, fatigue, and myoglobinuria. The
infantile form may include myopathy, mental retardation, cataracts, joint contractures,
and death during childhood. The late-onset form consists of progressive muscle weakness
developing in adults.
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Assess history of muscle weakness.
Monitor hemoglobin and reticulocyte count and renal function in cases of
myoglobinuria. Perform ultrasonography to evaluate the presence of
gallstones in case of hyperbilirubinemia. Evaluate cardiac and respiratory
function if necessary, particularly in the infantile form (clinical aspects,
radiographs, echocardiography, pulmonary function tests). Check renal function in the
presence of myoglobinuria.
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Tourniquets may precipitate painful
muscle cramps. Maintain normothermia to prevent shivering in the
postoperative period, which could trigger severe muscle cramps and
myoglobinuria. Careful intraoperative positioning is needed in patients with
myalgia and weakness. Postoperative ventilatory support can be necessary in
severe forms.
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Avoid succinylcholine. Use of
nondepolarizing muscle relaxants should not cause ...