Ocular manifestations of mitochondrial neurogastrointestinal encephalomyopathy: A case report and literature review

Abstract

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive multisystem disorder that often presents with gastrointestinal and neurological symptoms. Here we report a 33‐year‐old male who presented with a 16‐year history of diarrhea with black stool and progressive weight loss. He complained of progressive bilateral blurred vision, upper eyelids heaviness, ocular motility impairment, and color blindness. Peripheral neuropathy, bilateral sensorineural deafness, hyperlactatemia, diabetes mellitus, hepatic steatosis, blood coagulation dysfunction, and diffuse leukoencephalopathy were detected in the systemic evaluation. Based on the novel homozygous pathogenic variant in the TYMP gene (c.1159+1G>A), he was diagnosed with MNGIE. On ophthalmic examinations, the thickness of the inner retina and ganglion cell complex significantly decreased. ERG showed diffusely decreased amplitudes. The electronegative electroretinogram, which was first reported in MNGIE, indicated a more severe inner retina impairment. The bilateral papillomacular bundle defect and central vision loss in MNGIE are consistent with classical mitochondrial optic neuropathies' features. According to the literature, pigmentary retinopathy, optic neuropathy, and abnormal pupillary reflexes are uncommon ocular features of MNGIE. This study contributes to a better understanding of ocular manifestations in MNGIE and demonstrates that MNGIE may have dyschromatopsia and an electronegative electroretinogram.

Response to “Letter to the editor” regarding “Rule out compound heterozygous exonic/deep intronic ABCA4 variants in an MNGIE patient with Stargardt disease”

“…We sincerely appreciate the kind comments from Professor Finsterer on our published work (Wang et al, 2023). We have carefully read the comments and would like to reply to them for scientific discussion.…”

“…Based on the principle of holistic diagnosis, we think mitochondrial dysfunction played a major role in this case considering the rapid progression of visual impairment and systemic symptoms. Some other MNGIE patients have also been reported to have visual impairment (Wang et al, 2023). However, the possibility of the independent existence of distinct diseases should be considered.…”

Rule out compound heterozygous exonic/deep intronic ABCA4 variants in an MNGIE patient with Stargardt disease

“…A neuropathy was described in the patient, which manifested as sensory disturbances and muscle weakness (Wang et al, 2023). However, the patient also had myopathy manifested by ptosis, ophthalmoparesis, and lactic acidosis (Wang et al, 2023).…”

“…A neuropathy was described in the patient, which manifested as sensory disturbances and muscle weakness (Wang et al, 2023). However, the patient also had myopathy manifested by ptosis, ophthalmoparesis, and lactic acidosis (Wang et al, 2023). We should know if the limb muscle weakness was really due to neuropathy or rather to a myopathy involving the limb muscles.…”

“…A second limitation is that HbA1c levels were not reported (Wang et al, 2023). Knowing the quality of diabetes control is critical, as poorly controlled diabetes can be complicated by diabetic retinopathy.…”