Neurofibromatosis Type 2 (NF2) is a rare autosomal dominant disorder characterized by bilateral vestibular schwannomas and a spectrum of central and peripheral nervous system tumors. Early diagnosis can be challenging, particularly in the absence of classic skin findings or in resource-constrained settings. We present the case of an 18-year-old female who developed progressive bilateral vision loss, hearing impairment, and a longstanding posterior cervical mass. Ophthalmic evaluation revealed bilateral optic atrophy, with profound visual impairment. Audiological testing confirmed bilateral sensorineural hearing loss. MRI of the brain and spine demonstrated bilateral cerebellopontine angle tumors consistent with vestibular schwannomas, along with extensive craniospinal tumors including spinal ependymoma and multiple schwannomas. Optical coherence tomography (OCT) revealed significant thinning of the retinal nerve fiber layer, consistent with optic neuropathy. The constellation of findings confirmed a diagnosis of Neurofibromatosis Type 2. The simultaneous occurrence of optic atrophy, bilateral vestibular schwannomas, and multiple spinal tumors illustrates the classic but complex presentation of NF2. This case highlights how multimodal diagnostic tools - including neuroimaging, audiological assessment, and OCT - play a vital role in confirming the diagnosis in patients with progressive multisystem neurological deficits. This case underscores the importance of considering NF2 in young patients with simultaneous multisystem neurologic deficits, even in the absence of cutaneous stigmata. A high index of clinical suspicion, supported by multimodal imaging, is essential for early diagnosis and appropriate multidisciplinary management in such complex presentations. The phenotypic spectrum of SPG7-related neurologic disorder includes uncomplicated spastic ataxia, complicated spastic ataxia, spinocerebellar ataxia, and isolated optic nerve atrophy. Although onset typically occurs in adulthood, it may start in infancy or as late as age 72 years. Initially the spastic paraplegia is typically characterized by insidiously progressive bilateral leg weakness and spasticity or cerebellar findings (ataxia, dysarthria, and dysphagia) or both. Other central nervous system findings include decreased visual acuity due to optic neuropathy, cognitive impairment, and dystonia. Peripheral nervous system involvement manifests as motor and sensory neuropathy, neuropathic pain, and amyotrophy. Associated musculoskeletal involvement includes pes cavus and scoliosis. Spasticity and ataxia are progressive and may result in wheelchair dependence. The diagnosis of SPG7-related neurologic disorder is established in a proband with suggestive findings and biallelic pathogenic variants in SPG7 identified by molecular genetic testing. Treatment of manifestations: Multidisciplinary care by specialists in neurology, ophthalmology, low vision services, audiology, urology, physiatry, occupational therapy, physical therapy, orthopedics, feeding therapy and nutrition, speech-language therapy, social work, psychology, and clinical genetics. Surveillance: Monitor existing manifestations, the individual's response to supportive care, and the emergence of new manifestations with routinely scheduled evaluations by treating specialists. SPG7-related neurologic disorder is inherited in an autosomal recessive manner. (Several studies have reported a single [heterozygous] pathogenic variant in SPG7 in individuals with SPG7-related neurologic disorder suggesting the possibility of autosomal dominant inheritance; however, the possibility of autosomal dominant inheritance remains controversial.) If both parents are known to be heterozygous for an SPG7 pathogenic variant, each sib of an affected individual has at conception a 25% chance of being affected, a 50% chance of being heterozygous, and a 25% chance of inheriting neither of the familial pathogenic variants. Once the SPG7 pathogenic variants have been identified in an affected family member, heterozygote testing for at-risk relatives and prenatal/preimplantation genetic testing for SPG7-related neurologic disorder are possible.

Mitochondria-associated paraplegin dysfunction is primarily linked to spastic paraplegia; however, genetic alterations in SPG7 have been associated with a broader spectrum of clinical symptoms. To identify disease-causing variants in the SPG7 gene, 437 patients with spastic ataxia, mitochondrial dysfunction-associated symptoms, or motoneuron lesions detected by EMG have been tested. We aimed to assess the clinical spectrum and determine the frequency of damaging variants within patient groups, particularly those less studied. Using ACMG criteria, we identified 10 pathogenic or likely pathogenic variants, 5 variants of uncertain significance with predicted damaging effects, and a probable risk factor variant in 58 patients. We identified 25 biallelic and 33 monoallelic cases. The most common variant was p. Leu78Ter (N = 23), followed by p. Ala510Val (N = 21). The point prevalence of SPG7-associated conditions in Hungary in 2024 is 0.46 per 100 000. In addition to well-characterized cohorts, SPG7 alterations were frequently identified in cohorts with multisystemic mitochondrial disease and lower motoneuron lesions. Multiple mtDNA deletions and histological abnormalities were consistently observed across all groups. In monoallelic cases, no evidence of a digenic effect involving AFG3L2 was found. Both autosomal dominant and recessive inheritance patterns were documented, with monoallelic cases typically presenting with a milder phenotype.

This study assessed the diagnostic potential of chromatic pupil campimetry (CPC) using relative maximal constriction amplitude (relMCA), pupillary light response (PLR) latency, and pupillary escape to differentiate optic neuropathies (ON) from healthy individuals and identify specific ON subtypes. CPC testing used red and blue stimuli at central (0°) and peripheral (20°) locations to measure relMCA, latency, and pupillary escape. Patients with various ON etiologies, including glaucoma (n = 20), optic nerve compression by meningioma (n = 18), chiasm compression (n = 4), Leber hereditary optic neuropathy (LHON; n = 4), and autosomal dominant optic atrophy (ADOA; n = 3), were tested. Linear mixed-effects models and post hoc Tukey tests were used to analyze differences across subgroups of ON etiologies and a healthy control group (n = 40), regarding signal eccentricities and locations. Pupillary escape was significantly higher in ON patients during central red stimulation (p = 0.0007). Glaucoma and meningioma groups showed reduced relMCA and prolonged latency for both stimuli compared to controls (p < 0.0001 to p = 0.0058). RelMCA during blue stimulation was lower in glaucoma patients than in ADOA (p = 0.0183). LHON patients exhibited significantly prolonged PLR latency during blue stimulation compared to healthy (p = 0.0284). CPC effectively distinguished glaucoma and meningioma from healthy controls but was less reliable for differentiating ON subtypes. Our results indicate, that central pupillary escape is associated with inner retinal dysfunction.

Mitochondrial dynamics, governed by fusion and fission, are crucial for maintaining cellular homeostasis, energy production, and stress adaptation. MFN2 and OPA1, key regulators of mitochondrial fusion, play essential roles beyond their structural functions, influencing bioenergetics, intracellular signaling, and quality control mechanisms such as mitophagy. Disruptions in these processes, often caused by MFN2 or OPA1 mutations, are linked to neurodegenerative diseases like Charcot-Marie-Tooth disease type 2A (CMT2A) and autosomal dominant optic atrophy (ADOA). This review explores the molecular mechanisms underlying mitochondrial fusion, the impact of MFN2 and OPA1 dysfunction on oxidative phosphorylation and autophagy, and their role in disease progression. Additionally, we discuss the divergent cellular responses to MFN2 and OPA1 mutations, particularly in terms of proliferation, senescence, and metabolic signaling. Finally, we highlight emerging therapeutic strategies to restore mitochondrial integrity, including mTOR modulation and autophagy-targeted approaches, with potential implications for neurodegenerative disorders. MFN2 hereditary motor and sensory neuropathy (MFN2-HMSN) is a classic axonal peripheral sensorimotor neuropathy, inherited in either an autosomal dominant (AD) manner (~90%) or an autosomal recessive (AR) manner (~10%). MFN2-HMSN is characterized by more severe involvement of the lower extremities than the upper extremities, distal upper-extremity involvement as the neuropathy progresses, more prominent motor deficits than sensory deficits, and normal (>42 m/s) or only slightly decreased nerve conduction velocities (NCVs). Postural tremor is common. Median onset is age 12 years in the AD form and age eight years in the AR form. The prevalence of optic atrophy is approximately 7% in the AD form and approximately 20% in the AR form. Molecular genetic testing establishes the diagnosis of MFN2-HMSN in 90% of probands with suggestive findings by identifying a heterozygous MFN2 pathogenic variant and in 10% of probands with suggestive findings by identifying biallelic MFN2 pathogenic variants. Treatment of manifestations: Neuropathy is often managed by a multidisciplinary team that includes a neurologist, a physiatrist, an orthopedic surgeon, and physical and occupational therapists. Symptomatic treatment relies on special shoes and/or ankle/foot orthoses to correct foot drop and aid walking; surgery as needed for severe pes cavus; forearm crutches, canes, wheelchairs as needed for mobility; exercise as tolerated; acetaminophen or nonsteroidal anti-inflammatory agents for musculoskeletal pain; treatment of neuropathic pain with tricyclic antidepressants or drugs such as carbamazepine or gabapentin. Optic atrophy is managed with low vision aids as per a low vision clinic, consultation with community vision services, and career/employment counseling. Surveillance: Routine evaluation by: a neurologist to assess disease progression; physical therapy to assess gross motor skills including gait and strength; occupational therapy to assess fine motor skills and coping strategies; and ophthalmologist and low vision clinic to assess visual acuity and need for modification of low vision aids, respectively. Agents/circumstances to avoid: Obesity (which makes ambulation more difficult); medications (e.g., vincristine, isoniazid, nitrofurantoin) known to cause nerve damage; alcohol and malnutrition (which can cause or exacerbate neuropathy). Approximately 90% of MFN2-HMSN is inherited an autosomal dominant (AD) manner, and approximately 10% is inherited in an autosomal recessive (AR) manner. Semi-dominant inheritance (i.e., an MFN2 pathogenic variant is associated with mild disease in the heterozygous state and more severe disease in the homozygous or compound heterozygous state) has been reported in two families. AD MFN2-HMSN. Most affected individuals have an affected parent; the proportion of individuals with a de novo MFN2 pathogenic variant is unknown. Each child of an affected individual has a 50% chance of inheriting the MFN2 pathogenic variant. AR MFN2-HMSN. At conception, each sib of an individual with autosomal recessive MFN2-HMSN has a 25% chance of being affected, a 50% chance of being an asymptomatic heterozygote (i.e., carrier), and a 25% chance of being unaffected and not a carrier. Once the MFN2 pathogenic variant(s) have been identified in an affected family member, prenatal testing for a pregnancy at increased risk and preimplantation genetic testing for MFN2-HMSN are possible.

X-linked variants in Filamin A (FLNA) are associated with the Ehlers-Danlos-syndrome-variant form of periventricular heterotopia, and autosomal dominant variants in ubiquitin C-terminal hydrolase L1 (UCHL1) are associated with a late-onset spastic ataxia, peripheral neuropathy and optic atrophy. Here we present a rare case involving both a novel heterozygous whole-gene deletion of UCHL1 and a heterozygous frameshift variant in the FLNA gene resulting in a complex phenotype. A 67-year-old female with a confirmed pathogenic variant in the FLNA gene, resulting in an enlarged aorta and joint pains, presented with a 4-year history of severe sensory ataxia, upper motor neuron signs, eye movement abnormalities and severe sensory loss. Neurophysiology including Somatosensory-evoked potentials confirmed the sensory loss as predominantly preganglionic with denervation. Genetic testing revealed a digenic cause of her complex presentation, confirming a pathogenic frameshift variant in the FLNA gene and a heterozygous loss of function deletion in the UCHL1 gene. To the best of our knowledge, this is the first case with concomitant pathogenic variants in the FLNA and UCHL1 genes which explain the complex phenotype. The severe preganglionic sensory loss is also a rare finding and expands the phenotype of UCHL1 variants.