First Case in Lithuania of an Autosomal Recessive Mutation in the DNAJC30 Gene as a Cause of Leber’s Hereditary Optic Neuropathy

Background: Leber’s hereditary optic neuropathy (LHON) is the most common mitochondrial disorder and an inherited optic neuropathy. Recently, two different LHON inheritance types have been discovered: mitochondrially inherited LHON (mtLHON) and autosomal recessive LHON (arLHON). Our case report is the first diagnosed case of arLHON in a patient of Lithuanian descent and confirms the DnaJ Heat Shock Protein Family (Hsp40) Member C30 (DNAJC30) c.152A>G p.(Tyr51Cys) founder variant. Case Presentation: A 34-year-old Lithuanian man complained of headache and sudden, painless loss of central vision in his right eye. On examination, the visual acuity of the right and left eyes was 0.1 and 1.0, respectively. Visual-field examination revealed a central scotoma in the right eye, and visual evoked potentials (VEPs) showed prolonged latency in both eyes. Optical coherence tomography showed thickening of the retinal nerve fiber layer in the upper quadrant of the optic disk in the left eye. Magnetic resonance imaging of the head showed evidence of optic nerve inflammation in the right eye. Blood tests were within normal range and showed no signs of inflammation. Retrobulbar neuritis of the right eye was suspected, and the patient was treated with steroids, which did not improve visual acuity. He later developed visual loss in the left eye as well. A genetic origin of the optic neuropathy was suspected, and a complete mitochondrial DNA analysis was performed, but it did not reveal any pathologic mutations. Over time, the visual acuity of both eyes slowly deteriorated, and the retinal nerve fiber layer (RNFL) thinning of the optic disks progressed. A multidisciplinary team of specialists concluded that vasculitis or infectious disease was unlikely to be the cause of the vision loss, and a genetic cause for the disease was still suspected, although a first-stage genetic test did not yield the diagnosis. Thirty-three months after disease onset, whole-exome sequencing revealed a pathogenic variant in the DNAJC30 gene, leading to the diagnosis of arLHON. Treatment with Idebenone was started 35 months after the onset of the disease, resulting in no significant worsening of the patient’s condition. Conclusion: This case highlights the importance of considering arLHON as a possible diagnosis for patients with optic neuropathy, because the phenotype of arLHON appears to be identical to that of mtLHON and cannot be distinguished by clinicians.