G. Vita et al., MUSCLE PHOSPHOGLYCERATE MUTASE (PGAM) DEFICIENCY IN THE 1ST CAUCASIANPATIENT - BIOCHEMISTRY, MUSCLE CULTURE AND P-31-MR SPECTROSCOPY, Journal of neurology, 241(5), 1994, pp. 289-294
Muscle phosphoglycerate mutase (PGAM) deficiency has been so far ident
ified in only six patients, five of these being African Americans. We
report the results of clinical, morphological, biochemical, muscle cul
ture and P-31-MR spectroscopy studies in the first Caucasian patient w
ith muscle PGAM deficiency. A 23-year-old man had a 10-year history of
cramps after physical exertion with one episode of pigmenturia. Neuro
logical examination and EMG study were normal. ECG and echocardiograph
y revealed hypertrophy of the interventricular septum and slight dilat
ation of the left chambers of the heart. Muscle biopsy revealed increa
sed glycogen content and some accumulation of mitochondria. Muscle PGA
M activity was markedly decreased (6.5% and 9.7% of control value in t
wo different biopsies). Citrate synthase and other mitochondrial respi
ratory chain enzyme activities were much higher than normal. In contra
st to the marked decrease of PGAM activity observed in muscle biopsy,
total enzyme activity in the patient's aneural muscle culture was norm
al, being represented exclusively by BB isoenzyme. The deficiency of P
GAM-MM isoenzyme was reproduced in the patient's innervated muscle cul
ture. Muscle P-31-MR spectroscopy showed accumulation of phosphomonoes
ters only on fast ''glycolytic'' exercise. On ''aerobic'' exercise, V(
max), calculated from the work-energy cost transfer function, showed a
n increase consistent with the morphological and biochemical evidence
of mitochondrial proliferation. This might represent a sort of compens
atory aerobic effort in an attempt to restore muscle power.