P 1106. Involvement of the Cardial Autonomous Nervous System in Mitochondrial Neurogastrointestinal Encephalopathy Syndrome
30 October 2018 (online)
Mitochondrial neurogastrointestinal encephalopathy (MNGIE) syndrome, inherited in an autosomal-recessive pattern, is caused by a mutation in the TYMP gene, which encodes for the cytosolic thymidine phosphorylase (TMP). This leads to a disorder in mitochondrial DNA replication and repair. Clinically, MNGIE is characterized by the association of gastrointestinal motility disorder, anorexia, peripheral neuropathy, chronically progredient external ophthalmoplegia, and leukoencephalopathy. Due to the insidious course with initially unspecific gastrointestinal symptomatology, this very rare disease, which predominantly manifests in childhood, is often diagnosed late. However, its prognosis depends on a timely diagnosis and therapy. An early clinical diagnosis could be aided by the detection of the involvement of other organ systems usually affected by MNGIE. So far, an involvement of the autonomous nervous system (ANS) has only been reported in the context of histopathological examinations of the intestinal innervation. However, when translating animal experiment findings on tissue expression of TMP in the ANS to humans, one would expect a disorder in the vegetative function of other organs as well. The question of an involvement of the autonomous cardiac afference, which could be detected using simple clinical means and used for an early diagnosis, has not been dealt with in casuistic publications so far.
Using the example of two adolescents with molecular genetically confirmed MNGIE, we shall report on the examination results regarding the autonomous control of the heart rhythm.
Methodology and Results: Both patients underwent a 24-hour ECG with calculation of the heart rate variability. In both cases, a distinct sinus tachycardia of ∼120/minute and a restriction of the heart rate variability in the sense of parasympathetic dysfunction without evidence of a cardiomyopathy were found.
Summary: Our electrocardiographic examination results point to a primary parasympathetic disorder of the autonomous heart regulation in MNGIE. Cases of unclear gastrointestinal pseudo-obstruction with additional sinus tachycardia and reduced heart rate variability should lead to a timely suspected diagnosis of MNGIE, so that substantiating biochemical and molecular genetic examinations could be initiated significantly earlier than usually done.