Mitochondrial Neurogastrointestinal Encephalomyopathy Syndrome Treated with Stem Cell Transplant: A Case Series and Literature Review.

Mitochondrial neurogastrointestinal encephalomyopathy syndrome is a rare autosomal recessive multisystem disorder caused by nuclear TYMP gene mutations, which leads to deficiency in thymidine phosphorylase enzyme. This deficiency then leads to mitochondrial dysfunction, which causes the features characteristic of this syndrome, including severe muscle wasting, gastrointestinal dysmotility, leukoencephalopathy, peripheral neuropathy, and ophthalmoplegia. Here, we present a case series of 3 patients with mitochondrial neurogastrointestinal encephalomyopathy from Saudi Arabia who underwent allogeneic stem cell transplant at King Faisal Specialist Hospital (Riyadh, Saudi Arabia). Two patients died within the first year of transplant, and the third is still alive but without improvement in clinical features. Allogeneic hematopoietic stem cell transplant-related mortality appears to be high; this may at least be partially related to established end-organ effects with decreased performance status. Although allogeneic hematopoietic stem cell transplant clearly affects correction of genetic and biochemical defects in mitochondrial neurogastrointestinal encephalomyopathy, its ability to reverse or improve established clinical manifestations has not been proven.