Thymidine phosphorylase gene mutation is not a primary cause of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE).
OBJECTIVE
The authors identified a patient with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), who completely fulfilled the clinical criteria with low thymidine phosphorylase (TP) activity. However, the same homozygotic S471L TP gene mutation was also found in her unaffected mother, but with normal TP activity. To elucidate the pathogenesis of MNGIE, we performed the analysis below.


METHODS
We analyzed the TP gene mutation in the proband and 145 unrelated individuals by direct sequence and restriction fragment length polymorphism (RFLP). TP activity was determined by the spectrophotometric method for each TP S471L genotype.


RESULTS
Among 145 normal persons, the S471L homozygote mutants were identified in 2.76% and their enzyme activity was normal.


CONCLUSIONS
TP gene mutation is not a primary cause of MNGIE, but with a mitochondrial deletion mutation, a single nucleotide polymorphism (SNP) of the TP gene may be crucial in the pathogenesis of MNGIE.
Kumagai
Yukie
Y
Department of Neurology, Fukushima Medical University, School of Medicine, Fukushima.
Sugiura
Yoshihiro
Y
Sugeno
Hidekazu
H
Takebayashi
Yuji
Y
Takenoshita
Seiichi
S
Yamamoto
Teiji
T