Mutations In C19orf12 Research Articles

Generation of two human iPSC lines, HMGUi004-A and FINCBi004-A, from fibroblasts of MPAN patients carrying pathogenic recessive mutations in the gene C19orf12

Mitochondrial membrane Protein-Associated Neurodegeneration (MPAN) is a lethal neurodegenerative disorder caused by mutations in the human gene C19orf12. The molecular mechanisms underlying the disorder are still unclear, and no established therapy is available. Here, we describe the generation and characterization of two human induced pluripotent stem cell (iPSC) lines derived from skin fibroblasts of two MPAN patients carrying homozygous recessive mutations in C19orf12. These iPSC lines represent a useful resource for future investigations on the pathology of MPAN, as well as for the development of successful treatments.

A novel C19ORF12 mutation in a MPAN family with the treatment of deferiprone

A novel C19ORF12 mutation in a MPAN family with the treatment of deferiprone

Autonomic nervous system dysfunction in cases of neurodegeneration associated with mutations in C19orf12

Autonomic nervous system dysfunction in cases of neurodegeneration associated with mutations in C19orf12

A novel C19ORF12 mutation in two MPAN sisters treated with deferiprone

BackgroundMitochondrial membrane protein-associated neurodegeneration (MPAN) is a rare and devastating disease caused by pathogenic mutations in C19orf12 gene. MPAN is characterized by pathological iron accumulation in the brain and fewer than 100 cases of MPAN have been described. Although the diagnosis of MPAN has achieved a great breakthrough with the application of the whole exome gene sequencing technology, the therapeutic effect of iron chelation therapy in MPAN remains controversial.Case presentationWe reported that two sisters from the same family diagnosed with MPAN had dramatically different responses to deferiprone (DFP) treatment. The diagnosis of MPAN were established based on typical clinical manifestations, physical examination, brain magnetic resonance imaging (MRI), cerebrospinal fluid analysis (CSF) and gene sequencing results. The clinical presentations of the two sisters with MPAN due to novel gene locus mutations were similar to those previously reported. There is no other difference in basic information except that the proband had a later onset age and fertility history. Both the proband and his second sister were treated with deferiprone (DFP), but they had dramatically different responses to the treatment. The proband’s condition deteriorated sharply after treatment with DFP including psychiatric symptoms and movement disorders. However, the second sister of the proband became relatively stable after receiving the DFP treatment. After four years of follow-up, the patient still denies any new symptoms of neurological deficits.ConclusionThe findings of this study enriched the MPAN gene database and indicated that DFP might ameliorate symptom progression in patients without severe autonomic neuropsychiatric impairment at the early stage of the disease.

A novel C19orf12 frameshift mutation in a MPAN pedigree impairs mitochondrial function and connectivity leading to neurodegeneration

BackgroundMitochondrial membrane protein‒associated neurodegeneration (MPAN) is a rare genetic disease characterized by progressive neurodegeneration with brain iron accumulations combined with neuronal α-synuclein and tau aggregations. Mutations in C19orf12 have been associated with both autosomal recessive and autosomal dominant inheritance patterns of MPAN. MethodsWe present clinical features and functional evidence from a Taiwanese family with autosomal dominant MPAN caused by a novel heterozygous frameshift and nonsense mutation in C19orf12, c273_274 insA (p.P92Tfs*9). To verify the pathogenicity of the identified variant, we examined the mitochondrial function, morphology, protein aggregation, neuronal apoptosis, and RNA interactome in p.P92Tfs*9 mutant knock-in SH-SY5Y cells created with CRISPR-Cas9 technology. ResultsClinically, the patients with the C19orf12 p.P92Tfs*9 mutation presented with generalized dystonia, retrocollis, cerebellar ataxia, and cognitive decline, starting in their mid-20s. The identified novel frameshift mutation is located in the evolutionarily conserved region of the last exon of C19orf12. In vitro studies revealed that the p.P92Tfs*9 variant is associated with impaired mitochondrial function, reduced ATP production, aberrant mitochondria interconnectivity and ultrastructure. Increased neuronal α-synuclein and tau aggregations, and apoptosis were observed under conditions of mitochondrial stress. Transcriptomic analysis revealed that the expression of genes in clusters related to mitochondrial fission, lipid metabolism, and iron homeostasis pathways was altered in the C19orf12 p.P92Tfs*9 mutant cells compared to control cells. ConclusionOur findings provide clinical, genetic, and mechanistic insight revealing a novel heterozygous C19orf12 frameshift mutation to be a cause of autosomal dominant MPAN, further strengthening the importance of mitochondrial dysfunction in the pathogenesis of MPAN.

NBIA Syndromes: A Step Forward from the Previous Knowledge.

A disturbed iron metabolism may damage brain and trigger disorders known as neurodegeneration with brain iron accumulation (NBIA). NBIAs are rare, inherited disorders in which responsible mutations affect the function of proteins that participate in tissue iron homeostasis. Accumulated iron, which may be recognized as a low signal intensity on T2-weighted MRI images, oftentimes points to a diagnosis. Recent genetic discoveries confirm that NBIA is not a homogenous group of diseases. Fifteen different NBIAs have been described to date; among these, autosomal recessive inheritance was reported in 13, and autosmal dominant and X-linked dominant inheritance in one disease, respectively. Among NBIAs, the most common is pantothenate kinase-associated neurodegeneration (PKAN-NBIA 1) (30%-50% of all NBIA cases), that occurrs as a consequence of the autosomal recessive mutation in PANK2 gene, followed by phospholipase 2-associated neurodegeneration (PLAN, NBIA 2), due to mutation in PLA2G6 gene, and mitochondrial membrane protein-associated neurodegeneration (MPAN) with the underlying C19orf12 mutation [Table 1]. NBIAs are characterized by complex motor presentations from early-onset degeneration and premature fatality to adult-onset parkinsonism and dystonia. Epileptic seizures, pyramidal signs, visual disorders, and cognitive deterioration can develop. NBIAs are often refractory to therapeutical strategies, although certain interventions may provide significant symptomatic relief in selected patients. In this review, we discuss the expanding clinical spectrum of these complex and rare syndromes, their genetic and imaging features, and potential therapeutical targets and strategies.

Secondary tauopathy in a genetic synucleinopathy, mitochondrial protein–associated neurodegeneration (MPAN)

AbstractBackgroundTauopathy and α‐synucleinopathy often occur together in human brain diseases but most commonly in the context of β‐amyloidosis. Tauopathy induced by α‐synucleinopathy in the absence of β‐amyloid has been demonstrated in vitro and in cultured cells but compelling examples of this in human disease rarely occur, most commonly in familial Parkinson's disease due to mutations in the α‐synuclein gene. Mitochondrial protein‐associated neurodegeneration (MPAN) due to mutations in C19orf12 produces neurodegeneration with brain iron accumulation as well as widespread α‐synucleinopathy. We report here on the findings and significance of associated tauopathy in MPAN.MethodFour patients with genetically confirmed MPAN were referred for brain autopsy and a complete histologic and immunohistochemical evaluation was undertaken for lesions and proteinopathies of common neurodegenerative diseases as well as the specific reported lesions of MPAN.ResultAll patients had hallmark pathologic features of MPAN including atrophy, gliosis, and iron accumulation involving the globus pallidus as well as abundant α‐synucleinopathy manifest as Lewy bodies and neurites thoughout the brain. Tauopathy was present in each case with neurofibrillary tangles distributed in Braak stages I to V with pretangles and more widely distributed tau‐positive dystrophic neurites. The distribution and regional burden of tauopathy was less than that of α‐synucleinopathy in each case. β‐amyloid or TDP‐43 abnormalities were not identified in any case.ConclusionThe lesional burden and distribution in MPAN are consistent with a pathogenetic model in which dysmetabolism of α‐synuclein is sufficient, in the absence of other common neurodegenerative pathologies, to induce tauopathy. Study of rare familial diseases such as MPAN may enhance our understanding of the pathogenesis of more common idiopathic neurodegenerative diseases.

Cardiac symptoms in cases of neurodegeneration associated with mutations in C19orf12

Introduction: Neurodegeneration with brain iron accumulation (NBIA) comprises a group of rare genetic disorders associated with progressive movement disorders and excessive iron accumulation in the brain. One of the NBIA subtypes, mitochondrial membrane protein-associated neurodegeneration (MPAN) is caused by a mutation in the orphan gene C19orf12, which role is not described yet. As MPAN is caused by dysfunction of the protein expressed in mitochondria we screened MPAN patients for heart disease, typical for mitochondrial diseases.

Is there heart disease in cases of neurodegeneration associated with mutations in C19orf12?

IntroductionIn mitochondrial membrane protein-associated neurodegeneration (MPAN), a subtype of neurodegeneration with brain iron accumulation (NBIA), patients suffer from optic nerve atrophy and dementia, which are also typical for another group of diseases, the mitochondrial diseases (MD). Around 30% of patients with MD have heart disease, commonly cardiomyopathy and arrhythmias, and 10% experience a major adverse cardiovascular event. The aim of this study was to assess cardiac involvement in MPAN. MethodsThirteen patients with MPAN were evaluated after written informed consent. All patients had echocardiography and 12 patients had 24-h Holter electrocardiogram (ECG) monitoring using 3-channel digital recorders. ResultsEchocardiography revealed normal values for the dimensions of all heart chambers. The systolic function of the left ventricle was normal in all cases. Right ventricle systolic impairment was found in three patients. 24-hour Holter ECG revealed predominant resting tachycardia during daytime with no physiological slowing of heart rate during sleep in seven cases. No significant arrhythmias were found. In nine patients, selected heart rate variability (HRV) parameters were lower than reference values. ConclusionCardiomyopathy, typical of MD, was not found in patients with MPAN. There were no significant arrhythmias, but disturbances in the circadian rhythm of the heart rate were observed in most cases. The decrease in HRV may reflect an early sign of autonomic dysfunction. A standard cardiac work-up is recommended for patients with MPAN to assess if additional treatment is needed.

P.158 Restless legs syndrome induced by quetiapine: A case report and review of the literature

Neurodegeneration with brain iron accumulation (NBIA) comprises a heterogeneous group of disorders with accumulation of iron in the brain, mostly basal ganglia. NBIA subtype mitochondrial membrane protein-associated neurodegeneration (MPAN) is caused by recently discovered mutations in C19orf12, which encodes a protein localized in the mitochondrial membrane.The present and past radiological features of 14 MPAN patients were analyzed.Clinical evaluation did not reveal novel findings: spastic para- and tetraparesis with muscle atrophy are typical for MPAN. Dysarthria, parkinsonism, and dystonia are very common but not present in all cases. Present brain imaging demonstrated increased iron levels in the globus pallidus (GP) and substantia nigra (SN) in all patients. In two cases first imaging didn't show typical hypointensity in GP and SN. A novel finding were white matter hyperintensities localized mainly in the periventricular region.WMH are observed in some MPAN patients, they are age dependent and localized periventricular. If they are due to altered brain and peripheral lipid metabolism remains unknown.

Brain iron and metabolic abnormalities in C19orf12 mutation carriers: A 7.0 tesla MRI study in mitochondrial membrane protein-associated neurodegeneration.

Mitochondrial membrane protein-associated neurodegeneration is an autosomal-recessive disorder caused by C19orf12 mutations and characterized by iron deposits in the basal ganglia. The aim of this study was to quantify iron concentrations in deep gray matter structures using quantitative susceptibility mapping MRI and to characterize metabolic abnormalities in the pyramidal pathway using 1 H MR spectroscopy in clinically manifesting membrane protein-associated neurodegeneration patients and asymptomatic C19orf12 gene mutation heterozygous carriers. We present data of 4 clinically affected membrane protein-associated neurodegeneration patients (mean age: 21.0 ± 2.9 years) and 9 heterozygous gene mutation carriers (mean age: 50.4 ± 9.8 years), compared to age-matched healthy controls. MRI assessments were performed on a 7.0 Tesla whole-body system, consisting of whole-brain gradient-echo scans and short echo time, single-volume MR spectroscopy in the white matter of the precentral/postcentral gyrus. Quantitative susceptibility mapping, a surrogate marker for iron concentration, was performed using a state-of-the-art multiscale dipole inversion approach with focus on the globus pallidus, thalamus, putamen, caudate nucleus, and SN. In membrane protein-associated neurodegeneration patients, magnetic susceptibilities were 2 to 3 times higher in the globus pallidus (P = 0.02) and SN (P = 0.02) compared to controls. In addition, significantly higher magnetic susceptibility was observed in the caudate nucleus (P = 0.02). Non-manifesting heterozygous mutation carriers exhibited significantly increased magnetic susceptibility (relative to controls) in the putamen (P = 0.003) and caudate nucleus (P = 0.001), which may be an endophenotypic marker of genetic heterozygosity. MR spectroscopy revealed significantly increased levels of glutamate, taurine, and the combined concentration of glutamate and glutamine in membrane protein-associated neurodegeneration, which may be a correlate of corticospinal pathway dysfunction frequently observed in membrane protein-associated neurodegeneration patients. © 2019 International Parkinson and Movement Disorder Society.

A Novel c19orf12 Mutation in Mitochondrial Membrane Protein-Associated Neurodegeneration

A Novel c19orf12 Mutation in Mitochondrial Membrane Protein-Associated Neurodegeneration

Mitochondrial membrane protein-associated neurodegeneration: a case report and literature review

ABSTRACTMitochondrial membrane protein-associated neurodegeneration (MPAN) is an autosomal recessive disorder caused by mutation in the C19orf12 gene. We report a compound heterozygous c.[32C>T];[205G>A;424A>G] (p.[Thr11Met];[Gly69Arg;Lys142Glu]) Czech patient who manifested with right foot dystonia, impaired handwriting, attention deficit, and signs of iron accumulation on brain MRI. Gradually, he developed dysarthria, spastic-dystonic gait, pedes cavi, and atrophy of leg muscles. Additionally, we report demographic parameters, clinical signs, and allelic frequencies of C19orf12 mutations of all published MPAN cases. We compared the most frequent mutations, p.Thr11Met and p.Gly69ArgfsX10; the latter was associated with younger age at onset and more frequent optic atrophy in homozygotes.

Chapter 19 - Neurodegeneration with brain iron accumulation

Neurodegeneration with brain iron accumulation (NBIA) comprises a clinically and genetically heterogeneous group of disorders affecting children and adults. These rare disorders are often first suspected when increased basal ganglia iron is observed on brain magnetic resonance imaging. For the majority of NBIA disorders the genetic basis has been delineated, and clinical testing is available. The four most common NBIA disorders include pantothenate kinase-associated neurodegeneration (PKAN) due to mutations in PANK2, phospholipase A2-associated neurodegeneration caused by mutation in PLA2G6, mitochondrial membrane protein-associated neurodegeneration from mutations in C19orf12, and beta-propeller protein-associated neurodegeneration due to mutations in WDR45. The ultrarare NBIA disorders are caused by mutations in CoASY, ATP13A2, and FA2H (causing CoA synthase protein-associated neurodegeneration, Kufor-Rakeb disease, and fatty acid hydroxylase-associated neurodegeneration, respectively). Together, these genes account for disease in approximately 85% of patients diagnosed with an NBIA disorder. New NBIA genes are being recognized with increasing frequency as a result of whole-exome sequencing, which is also facilitating early ascertainment of patients whose phenotype is often nonspecific.

Evolution and novel radiological changes of neurodegeneration associated with mutations in C19orf12

IntroductionNeurodegeneration with brain iron accumulation (NBIA) comprises a heterogeneous group of disorders with accumulation of iron in the brain, mostly basal ganglia. NBIA subtype mitochondrial membrane protein-associated neurodegeneration (MPAN) is caused by recently discovered mutations in C19orf12, which encodes a protein localized in the mitochondrial membrane. MethodsThe present and past radiological features of 14 MPAN patients were analyzed. ResultsClinical evaluation did not reveal novel findings: spastic para- and tetraparesis with muscle atrophy are typical for MPAN. Dysarthria, parkinsonism, and dystonia are very common but not present in all cases. Present brain imaging demonstrated increased iron levels in the globus pallidus (GP) and substantia nigra (SN) in all patients. In two cases first imaging didn't show typical hypointensity in GP and SN. A novel finding were white matter hyperintensities localized mainly in the periventricular region. ConclusionsWMH are observed in some MPAN patients, they are age dependent and localized periventricular. If they are due to altered brain and peripheral lipid metabolism remains unknown.

The p.Thr11Met mutation in c19orf12 is frequent among adult Turkish patients with MPAN

IntroductionMutations in the C19orf12 gene cause mitochondrial membrane protein associated neurodegeneration (MPAN), an autosomal recessive form of neurodegeneration with brain iron accumulation (NBIA). A limited number of patients with C19orf12 mutations, particularly those with adult onset of symptoms, have been reported. MethodsWe sequenced the entire coding region of C19orf12 in 15 Turkish adult probands with idiopathic NBIA. We also performed haplotype analysis in families with a recurrent C19orf12 mutation. Clinical features were collected using a standardized form. ResultsNine of our 15 probands (60%) carried the homozygous c.32C > T mutation in C19orf12 (predicted protein effect: p.Thr11Met). This homozygous mutation co-segregated with the disease in all affected relatives available for testing (16 homozygous subjects).Haplotypes across the C19orf12 locus were identical for a very small region, closest to the mutation, suggesting an old founder, or, two independent founders. The clinical phenotype was characterized by adult onset in most cases (mean 24.5 years, range 10–36), and broad spectrum, including prominent parkinsonism, pyramidal signs, psychiatric disturbances, cognitive decline, and motor axonal neuropathy, in various combinations. On T2- or susceptibility weighted-MRI images, all patients displayed bilateral hypointensities in globus pallidus and substantia nigra, without an eye-of-the-tiger sign; however, hyperintense streaking of the medial medullary lamina between the external and internal parts of globus pallidus was observed frequently. ConclusionThe C19orf12 p.Thr11Met mutation is frequent among adult Turkish patients with MPAN. These findings contribute to the characterization of this important NBIA form, and have direct implications for genetic testing of patients of Turkish origin.

Mutations in C19orf12 and intronic repeat expansions in C9orf72 not observed in Iranian Parkinson's disease patients

Various neurodegenerative disorders share some clinical features that sometimes renders differential diagnosis challenging. Genetic-based classification also has limitations as mutations in the same gene are sometimes associated with different clinically based diagnoses. In this light, we screened the C19orf12 neurodegeneration with brain iron accumulation (NBIA) causing gene and the C9orf72 intronic expansion mutation that is cause of amyotrophic lateral sclerosis in 186 Iranian Parkinson's disease (PD) patients. C19orf12 has previously been screened in PD patients in only one study, and to the best of our knowledge neither gene has ever been screened in a PD cohort from a Middle East population. The study was justified because mutations in C19orf12 had previously been shown to be common in Iranian neurodegeneration with brain iron accumulation patients and all the patients with mutations in this gene had exhibited Parkinsonism features. The C9orf72 intronic expansion mutation was screened because the mother of an Iranian amyotrophic lateral sclerosis patient with the expansion who had been diagnosed with PD also harbored the expansion. The screenings did not identify disease causing variations in either of the genes among the PD patients screened.

Retinal and optic nerve abnormalities in neurodegeneration associated with mutations in C19orf12 (MPAN)

BackgroundMitochondrial membrane protein-associated neurodegeneration (MPAN) is an neurodegeneration with brain iron accumulation (NBIA) subtype with mutation of C19orf12. Optic atrophy is one of the core symptoms in almost all MPAN cases, but the detailed ophthalmologic features of MPAN patients have not yet been described. MethodsAll consecutive symptomatic, gene proven MPAN patients underwent a detailed ophthalmological examination: best corrected visual acuity (BCVA), slit lamp examination, dilated fundus examination, tonometry, optical coherent tomography (OCT) and electrophysiological examinations. The total thickness of the macula (Mth) and the retinal nerve fiber layer (RNFL) were measured separately. ResultsSix males aged 18 to 21years were examined. Dilated fundus examination revealed complete optic disc paleness in 5 patients. In all patients, the Mth was normal. The total RNFL was thin in five patients. The latencies of PVEP were prolonged in all patients except one. In all cases, the ERG latencies and amplitudes were normal under both scotopic and photopic conditions. One patient, carrying different mutation and with different disease course, had a normal optic nerve head, normal RNFL thickness and PVEP latencies. ConclusionsOptic nerve atrophy seems to be genotype-dependent in MPAN patients but is typical for the disease. This phenomenon, together with normal ERG examination, is most distinctive for MPAN.

Behr syndrome with homozygous C19ORF12 mutation

ObjectiveBehr syndrome, first described in 1909 by the ophthalmologist Carl Behr, is a clinical entity characterised by a progressive optic atrophy, ataxia, pyramidal signs and mental retardation. Some reported cases have been found to carry mutations in the OPA1, OPA3 or C12ORF65 genes which are known causes of pure optic atrophy or optic atrophy complicated by movement disorder. MethodsWe present the long-term observation of two Turkish sisters with Behr syndrome. We performed neurophysiological, imaging and molecular genetic studies to identify the underlying genetic cause in our patients. ResultsMagnetic resonance imaging of the brain showed bilateral hypointense signals in the basal ganglia which prompted us to consider neurodegeneration with brain iron accumulation (NBIA) as a differential diagnosis. Molecular genetic studies revealed a homozygous mutation in the C19ORF12 gene which has been previously reported in patients with a subtype of NBIA, mitochondrial membrane protein-associated neurodegeneration (MPAN). ConclusionWe expand the spectrum of genetic causes of Behr syndrome. Genetic testing of patients presenting with Behr syndrome should include C19ORF12 mutation screening.

Mutations of C19orf12, coding for a transmembrane glycine zipper containing mitochondrial protein, cause mis-localization of the protein, inability to respond to oxidative stress and increased mitochondrial Ca²⁺.

Mutations in C19orf12 have been identified in patients affected by Neurodegeneration with Brain Iron Accumulation (NBIA), a clinical entity characterized by iron accumulation in the basal ganglia. By using western blot analysis with specific antibody and confocal studies, we showed that wild-type C19orf12 protein was not exclusively present in mitochondria, but also in the Endoplasmic Reticulum (ER) and MAM (Mitochondria Associated Membrane), while mutant C19orf12 variants presented a different localization. Moreover, after induction of oxidative stress, a GFP-tagged C19orf12 wild-type protein was able to relocate to the cytosol. On the contrary, mutant isoforms were not able to respond to oxidative stress. High mitochondrial calcium concentration and increased H2O2 induced apoptosis were found in fibroblasts derived from one patient as compared to controls. C19orf12 protein is a 17 kDa mitochondrial membrane-associated protein whose function is still unknown. Our in silico investigation suggests that, the glycine zipper motifs of C19orf12 form helical regions spanning the membrane. The N- and C-terminal regions with respect to the transmembrane portion, on the contrary, are predicted to rearrange in a structural domain, which is homologs to the N-terminal regulatory domain of the magnesium transporter MgtE, suggesting that C19orf12 may act as a regulatory protein for human MgtE transporters. The mutations here described affect respectively one glycine residue of the glycine zipper motifs, which are involved in dimerization of transmembrane helices and predicted to impair the correct localization of the protein into the membranes, and one residue present in the regulatory domain, which is important for protein-protein interaction.