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Neurodegeneration with brain iron accumulation (NBIA) is a term used for a group of hereditary neurological disorders with abnormal accumulation of iron in basal ganglia. It is clinically and genetically heterogeneous with symptoms such as dystonia, dysarthria, Parkinsonism, intellectual disability, and spasticity. The age at onset and rate of progression are variable among individuals. Current therapies are exclusively symptomatic and unable to hinder the disease progression. Approximately 16 genes have been identified and affiliated to such condition with different functions such as iron metabolism (only two genes: Ferritin Light Chain (FTL) Ceruloplasmin (CP)), lipid metabolism, lysosomal functions, and autophagy process, but some functions have remained unknown so far. Subgroups of NBIA are categorized based on the mutant genes. Although in the last 10 years, the development of whole-exome sequencing (WES) technology has promoted the identification of disease-causing genes, there seem to be some unknown genes and our knowledge about the molecular aspects and pathogenesis of NBIA is not complete yet. There is currently no comprehensive study about the NBIA in Iran; however, one of the latest discovered NBIA genes, GTP-binding protein 2 (GTPBP2), has been identified in an Iranian family, and there are some patients who have genetically remained unknown.

Our clinical series comprises 124 patients with movement disorders (MDs) and/or ataxia with cerebellar atrophy (CA), many of them showing signs of neurodegeneration with brain iron accumulation (NBIA). Ten NBIA genes are accepted, although isolated cases compatible with abnormal brain iron deposits are known. The patients were evaluated using standardised clinical assessments of ataxia and MDs. First, NBIA genes were analysed by Sanger sequencing and 59 patients achieved a diagnosis, including the detection of the founder mutation PANK2 p.T528M in Romani people. Then, we used a custom panel MovDisord and/or exome sequencing; 29 cases were solved with a great genetic heterogeneity (34 different mutations in 23 genes). Three patients presented brain iron deposits with Fe-sensitive MRI sequences and mutations in FBXO7, GLB1, and KIF1A, suggesting a NBIA-like phenotype. Eleven patients showed very early-onset ataxia and CA with cortical hyperintensities caused by mutations in ITPR1, KIF1A, SPTBN2, PLA2G6, PMPCA, and PRDX3. The novel variants were investigated by structural modelling, luciferase analysis, transcript/minigenes studies, or immunofluorescence assays. Our findings expand the phenotypes and the genetics of MDs and ataxias with early-onset CA and cortical hyperintensities, and highlight that the abnormal brain iron accumulation or early cerebellar gliosis may resembling a NBIA phenotype.

Non-invasive measures of brain iron content would be of great benefit in neurodegeneration with brain iron accumulation (NBIA) to serve as a biomarker for disease progression and evaluation of iron chelation therapy. Although magnetic resonance imaging (MRI) provides several quantitative measures of brain iron content, none of these have been validated for patients with a severely increased cerebral iron burden. We aimed to validate R2* as a quantitative measure of brain iron content in aceruloplasminemia, the most severely iron-loaded NBIA phenotype. Tissue samples from 50 gray- and white matter regions of a postmortem aceruloplasminemia brain and control subject were scanned at 1.5 T to obtain R2*, and biochemically analyzed with inductively coupled plasma mass spectrometry. For gray matter samples of the aceruloplasminemia brain, sample R2* values were compared with postmortem in situ MRI data that had been obtained from the same subject at 3 T – in situ R2*. Relationships between R2* and tissue iron concentration were determined by linear regression analyses. Median iron concentrations throughout the whole aceruloplasminemia brain were 10 to 15 times higher than in the control subject, and R2* was linearly associated with iron concentration. For gray matter samples of the aceruloplasminemia subject with an iron concentration up to 1000 mg/kg, 91% of variation in R2* could be explained by iron, and in situ R2* at 3 T and sample R2* at 1.5 T were highly correlated. For white matter regions of the aceruloplasminemia brain, 85% of variation in R2* could be explained by iron. R2* is highly sensitive to variations in iron concentration in the severely iron-loaded brain, and might be used as a non-invasive measure of brain iron content in aceruloplasminemia and potentially other NBIA disorders.

Mitochondrial membrane protein-associated neurodegeneration (MPAN) is a relentlessly progressive neurodegenerative disorder caused by mutations in the C19orf12 gene. C19orf12 has been implicated in playing a role in lipid metabolism, mitochondrial function, and autophagy, however, the precise functions remain unknown. To identify new robust cellular targets for small compound treatments, we evaluated reported mitochondrial function alterations, cellular signaling, and autophagy in a large cohort of MPAN patients and control fibroblasts. We found no consistent alteration of mitochondrial functions or cellular signaling messengers in MPAN fibroblasts. In contrast, we found that autophagy initiation is consistently impaired in MPAN fibroblasts and show that C19orf12 expression correlates with the amount of LC3 puncta, an autophagy marker. Finally, we screened 14 different autophagy modulators to test which can restore this autophagy defect. Amongst these compounds, carbamazepine, ABT-737, LY294002, oridonin, and paroxetine could restore LC3 puncta in the MPAN fibroblasts, identifying them as novel potential therapeutic compounds to treat MPAN. In summary, our study confirms a role for C19orf12 in autophagy, proposes LC3 puncta as a functionally robust and consistent readout for testing compounds, and pinpoints potential therapeutic compounds for MPAN.

The term neurodegeneration with brain iron accumulation (NBIA) brings together a broad set of progressive and disabling neurological genetic disorders in which iron is deposited preferentially in certain areas of the brain. Among NBIA disorders, the most frequent subtype is pantothenate kinase-associated neurodegeneration (PKAN) caused by pathologic variants in the PANK2 gene codifying the enzyme pantothenate kinase 2 (PANK2). To date, there are no effective treatments to stop the progression of these diseases. This review discusses the utility of patient-derived cell models as a valuable tool for the identification of pharmacological or natural compounds for implementing polytarget precision medicine in PKAN. Recently, several studies have described that PKAN patient-derived fibroblasts present the main pathological features associated with the disease including intracellular iron overload. Interestingly, treatment of mutant cell cultures with various supplements such as pantothenate, pantethine, vitamin E, omega 3, α-lipoic acid L-carnitine or thiamine, improved all pathophysiological alterations in PKAN fibroblasts with residual expression of the PANK2 enzyme. The information provided by pharmacological screenings in patient-derived cellular models can help optimize therapeutic strategies in individual PKAN patients.

Mitochondrial Membrane Protein-Associated Neurodegeneration is a rare monogenic form of neurodegeneration characterized by iron accumulation in the brain. It is due to variants in the orphan gene C19orf12. Since its definition in 2011, many scientific groups have investigated the clinical features and molecular underpinnings of the disorder. In this review, we summarize the main points of progress in this field, trying to highlight the issues that need further attention and efforts to speed up the diagnostic path, improve the existing treatment options, and define targeted therapies.

Background Neurodegeneration with brain iron accumulation (NBIA) comprises a genetically and clinically heterogeneous group of rare neurological disorders characterized particularly by iron accumulation in the basal ganglia. To date, 15 genes have been associated with NBIA. Among them, WDR45, linked to beta‐propeller protein‐associated neurodegeneration (BPAN), represents the only X‐linked dominant subtype of NBIA. Herein, clinical, electrophysiological, and neuroimaging evaluations were used to broaden the understanding of BPAN in a newly reported case series. Methods This study included 10 individuals with BPAN, categorized into three age groups. WDR45 variant data retrieved from next‐generation sequencing or Sanger sequencing were reviewed and reassessed. Comprehensive clinical evaluations including magnetic resonance imaging (MRI), fluorodeoxyglucose positron emission tomography (FDG‐PET), and video electroencephalographic monitoring were conducted. Results The clinical manifestations were highly heterogeneous, with cognitive impairment being a consistent finding among the patients, with variable severity. The associated WDR45 variants are likely to exert loss‐of‐function effects. Electroencephalogram (EEG) abnormalities included age‐dependent background slowing and epileptiform discharges. MRI indicated a characteristic pattern, while two patients lacked these typical findings. FDG‐PET imaging demonstrated hypometabolism extending beyond cerebral structures, with predominant cerebellar and pontine involvement in pediatric patients and frontoparietal hypometabolism in adults. Conclusions This study contributes further to our understanding of the heterogeneous clinical spectrum of BPAN. Genotype–phenotype correlation in BPAN remains unclear due to the absence of sufficiently large cohorts in the literature, including the present study. Nevertheless, even within this small sample, the phenotypic heterogeneity observed among individuals harboring the same genotype highlights the biological complexity of the disease. Neuroimaging findings may reflect progressive and widespread neurological involvement in an age‐dependent pattern, whereas EEG data suggest that epilepsy severity tends to decrease after adolescence.

Variants of the C19ORF12-gene have been described in patients with spastic paraplegia type 43 and in patients with mitochondrial membrane protein-associated neurodegeneration (MPAN), a subtype of neurodegeneration associated with brain iron accumulation (NBIA). In both subtypes optic atrophy and neuropathy have been frequently described. This case report describes a patient with bilateral optic atrophy and severe distal muscle weakness based on motor neuropathy without involvement of the central nervous system. Exome sequencing revealed a homozygous pathogenic missense variant (c.187G>C;p.Ala63Pro) of the C19ORF12-gene while iron deposits were absent on repeat MR-imaging of the brain, thus showing that peripheral neuropathy and optic neuropathy can be the sole manifestations of the C19ORF12-related disease spectrum whereby iron accumulation in the brain may be absent. •C19ORF12 variants have been described in mitochondrial membrane protein-associated neurodegeneration.•Central nervous system features predominate but optic neuropathy and peripheral neuropathy are frequently found.•Peripheral and optic neuropathy can be the sole manifestations.

•Almost exclusively homozygous PANK2 mutations in 22 PKAN patients from 13 families.•At least four PKAN subtypes are represented within the cohort.•A catalogue of all reported PANK2 mutations. Pantothenate kinase-associated neurodegeneration (PKAN) is caused by mutations of the pantothenate kinase 2 (PANK2) gene. The major clinical sign of PKAN is dystonia and the eye-of-the-tiger pattern on the MRI has been a clue for the diagnosis. We aim to discuss clinical and genetic findings of 22 PKAN patients from 13 families. Twenty-two patients were clinically diagnosed with PKAN and screened for PANK2 mutations. The patients were classified according to their onset age and progression rate. Mutation screening revealed 5 novel and 7 previously reported sequence variants in PANK2. The variants identified were in the form of missense changes, small exonic deletions and intronic mutations with a probable splicing effect. The presenting features were dystonia and gait disturbance in early onset patients, whereas the presenting symptoms were variable for the late onset group. The progression rate of the disease was not uniform. The current report is the first patient series of PKAN from Turkey that expands the clinical and genetic spectrum of the disease.