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Thermolability of 5,10-methylenetetrahydrofolate reductase (MTHFR) was examined as a possible cause of mild hyperhomocysteinemia in patients with premature vascular disease. Control subjects and vascular patients with mild hyperhomocysteinemia and with normohomocysteinemia were studied. The mean (+/- SD) specific MTHFR activity in lymphocytes of 22 control subjects was 15.6 (+/- 4.7) nmol CH2O/mg protein/h (range: 9.1-26.6), and the residual activity (+/- SD) after heat inactivation for 5 min at 46 degrees C was 55.3 (+/- 12.0)% (range: 35.9-78.3). By measurement of MTHFR activity, two distinct subgroups of hyperhomocysteinemic patients became evident. One group (n = 11) had thermolabile MTHFR with a mean (+/- SD) specific activity of 8.7 (+/- 2.1) nmol CH2O/mg protein/h (range: 5.5-12.7) and a residual activity, after heat inactivation, ranging from 0% to 33%. The other group (n = 28) had normal specific activity (+/- SD) of 21.5 (+/- 7.2) nmol CH2O/mg protein/h (range: 10.0-39.0) and a normal residual activity (+/- SD) of 53.8 (+/- 9.2)% (range: 33.1-71.5) after heat inactivation. The mean (+/- SD) specific activity of 29 normohomocysteinemic patients was 20.7 (+/- 6.5) nmol CH2O/mg protein/h (range: 9.4-33.8), and the mean (+/- SD) residual activity after heat inactivation was 58.2 (+/- 10.2)% (range: 43.0-82.0). Thus, in 28% of the hyperhomocysteinemic patients with premature vascular disease, abnormal homocysteine metabolism could be attributed to thermolabile MTHFR.
A M Engbersen, and
D G Franken, and
G H Boers, and
E M Stevens, and
F J Trijbels, and
H J Blom
September 1998,
American journal of human genetics,
A M Engbersen, and
D G Franken, and
G H Boers, and
E M Stevens, and
F J Trijbels, and
H J Blom
June 1997,
Journal of neurology, neurosurgery, and psychiatry,
A M Engbersen, and
D G Franken, and
G H Boers, and
E M Stevens, and
F J Trijbels, and
H J Blom
March 2011,
Amyotrophic lateral sclerosis : official publication of the World Federation of Neurology Research Group on Motor Neuron Diseases,
A M Engbersen, and
D G Franken, and
G H Boers, and
E M Stevens, and
F J Trijbels, and
H J Blom
January 2001,
European journal of clinical investigation,
A M Engbersen, and
D G Franken, and
G H Boers, and
E M Stevens, and
F J Trijbels, and
H J Blom
January 2000,
Journal of nephrology,
A M Engbersen, and
D G Franken, and
G H Boers, and
E M Stevens, and
F J Trijbels, and
H J Blom
May 2002,
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A M Engbersen, and
D G Franken, and
G H Boers, and
E M Stevens, and
F J Trijbels, and
H J Blom
October 2003,
The New England journal of medicine,
A M Engbersen, and
D G Franken, and
G H Boers, and
E M Stevens, and
F J Trijbels, and
H J Blom
October 2003,
The New England journal of medicine,
A M Engbersen, and
D G Franken, and
G H Boers, and
E M Stevens, and
F J Trijbels, and
H J Blom
October 1988,
American journal of human genetics,
A M Engbersen, and
D G Franken, and
G H Boers, and
E M Stevens, and
F J Trijbels, and
H J Blom
May 1997,
Lancet (London, England),
