A mitochondrial DNA depletion syndrome that is characterized by ophthalmoplegia, ptosis, gastrointestinal dysmotility, cachexia, peripheral neuropathy, and brain MRI changes, known as the MNGIE phenotype, and has_material_basis_in autosomal recessive homozygous or compound heterozygous mutation in the ribonucleotide reductase M2 B gene on chromosome 8q22.