Phenotypic Heterogeneity in Patients with Mutations in the Mitochondrial Complex I Assembly Gene NDUFAF5.

BACKGROUND: Rare mutations in NADH:ubiquinone oxidoreductase complex assembly factor 5 (NDUFAF5) are linked to Leigh syndrome. OBJECTIVE: We aimed to describe clinical characteristics and functional findings in a patient cohort with NDUFAF5 mutations. METHODS: Patients with biallelic NDUFAF5 mutations were recruited from multi-centers in Taiwan. Clinical, laboratory, radiological, and follow-up features were recorded and mitochondrial assays were performed in patients' skin fibroblasts. RESULTS: Nine patients from seven unrelated pedigrees were enrolled, eight homozygous for c.836 T > G (p.Met279Arg) in NDUFAF5 and one compound heterozygous for p.Met279Arg. Onset age had a bimodal distribution. The early-onset group (age <3 years) presented with psychomotor delay, seizure, respiratory failure, and hyponatremia. The late-onset group (age ≥5 years) presented with normal development, but slowly progressive dystonia. Combing 25 previously described patients, the p.Met279Arg variant was exclusively identified in Chinese ancestry. Compared with other groups, patients with late-onset homozygous p.Met279Arg were older at onset (P = 0.008), had less developmental delay (P = 0.01), less hyponatremia (P = 0.01), and better prognosis with preserved ambulatory function into early adulthood (P = 0.01). Bilateral basal ganglia necrosis was a common radiological feature, but brainstem and spinal cord involvement was more common with early-onset patients (P = 0.02). A modifier gene analysis showed higher concomitant mutation burden in early-versus late-onset p.Met279Arg homozygous cases (P = 0.04), consistent with more impaired mitochondrial function in fibroblasts from an early-onset case than a late-onset patient. CONCLUSIONS: The p.Met279Arg variant is a common mutation in our population with phenotypic heterogeneity and divergent prognosis based on age at onset. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Lovastatin protects neurite degeneration in LRRK2-G2019S parkinsonism through activating the Akt/Nrf pathway and inhibiting GSK3ß activity.

Parkinson's disease (PD) is a progressive neurodegenerative disorder that lacks a disease-modifying therapy. Leucine-rich repeat kinase 2 (LRRK2) was implicated as the most common genetic cause of PD. We previously established a LRRK2-G2019S Drosophila model that displayed the crucial phenotypes of LRRK2 parkinsonism. Here, we used a two-step approach to identify compounds from the FDA-approved licensed drug library that could suppress neurite degeneration in LRRK2-G2019S parkinsonism. Of 640 compounds, 29 rescued neurite degeneration phenotypes and 3 restored motor disability and dopaminergic neuron loss in aged LRRK2-G2019S flies. Of these three drugs, lovastatin had the highest lipophilicity, which facilitated crossing the blood-brain barrier. In LRRK2-G2019S knock-in mice and stably transfected human dopaminergic cells, lovastatin significantly rescued neurite degeneration in a dose-dependent manner, within a range of 0.05-0.1 µm The beneficial effect of lovastatin was exerted by activating anti-apoptotic Akt/Nrf signaling and decreasing caspase 3 levels. We also observed that lovastatin inhibited GSK3ß activity, a kinase downstream of Akt, by up-regulating GSK3ß (Ser9) phosphorylation. This inhibition subsequently decreased tau phosphorylation, which was linked to neuronal cytoskeleton instability. Conversely, pre-treatment with the Akt inhibitor, A6730, blocked the lovastatin-induced neuroprotective effect. The rescuing effects of lovastatin in dendritic arborization of LRRK2-G2019S neurons were abolished by co-expressing either a mutant allele of Akt (Akt104226) or a constitutively active form of GSK3ß (sggS9A). Our findings demonstrated that lovastatin restored LRRK2-G2019S neurite degeneration by augmenting Akt/NRF2 pathway and inhibiting downstream GSK3ß activity, which decreased phospho-tau levels. We suggested that lovastatin is a potential disease-modifying agent for LRRK2-G2019S parkinsonism.

A limb-girdle myopathy phenotype of RUNX2 mutation in a patient with cleidocranial dysplasia: a case study and literature review.

BACKGROUND: Cleidocranial dysplasia (CCD) is a rare hereditary disorder that arises from heterozygous loss of function mutations in the runt-related transcription factor 2 (RUNX2) gene. As RUNX2 is mainly expressed in osteoblasts, CCD typically affects the skeletal and dental systems. Few studies have investigated RUNX2 mutation effects on non-skeletal systems. Here, we describe limb-girdle myopathy, an uncommon phenotype of CCD, in a patient with a heterozygous missense mutation (p.R225Q) in the RUNX2 gene. CASE PRESENTATION: A 58 year-old man presented with progressive back pain and six months of weakness in the proximal parts of all four limbs. Physical examinations showed that he was short in stature (height, 164.4 cm; weight, 79.1 kg) with a dysmorphic face, including hypertelorism, midface hypoplasia, and chin protrusion. At a young age, he had received orthodontic surgery, due to dental abnormalities. Neurological examinations revealed sloping shoulders, weakness, and atrophy in the proximal areas of the arms, shoulder girdle muscles, and legs. The deep tendon reflex and sensory system were normal. Radiological examinations revealed mild scoliosis, shortened clavicles, and a depressed skull bone, which were consistent with a clinical diagnosis of CCD. Electromyography (EMG) studies showed myogenic polyphasic waves in the deltoid, biceps brachii, and rectus femoris muscles. Instead, the EMG findings were normal in the first dorsal interosseous, tibialis anterior and facial muscles. The EMG findings were compatible with a limb-girdle pattern with facial sparing. The patient's family history showed his father and eldest daughter with similar dysmorphic faces, skeletal disorders and proximal upper extremity weakness. We sequenced the RUNX2 gene and discovered a heterozygous missense mutation (c.G674A, p.R225Q), which altered the C-terminal end of the RUNX2 protein. This mutation was predicted to inactivate the protein and might affect its interactions with other proteins. This mutation co-segregated with the disease phenotypes in the family. CONCLUSIONS: We described limb-girdle myopathy in a patient with CCD that carried a heterozygous RUNX2 missense mutation. This uncommon phenotype expanded the phenotypic spectrum of the RUNX2 p.R225Q mutation. The role of RUNX2 in myogenic development merits future studies. Our findings remind clinicians that myopathic patients with myopathies combined with facial dysmorphism and shortened clavicles should consider the diagnosis of CCD.

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

BACKGROUND: Mitochondrial 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. METHODS: We 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. RESULTS: Clinically, 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. CONCLUSION: Our 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.

Genetic analysis of IMPDH2 gene in Taiwanese patients with isolated or combined dystonia.

The inosine monophosphate dehydrogenase gene (IMPDH2) was recently reported as a novel gene associated with autosomal dominantly inherited dystonia. We investigated 245 Taiwanese patients with molecularly unassigned isolated or combined dystonia without features of neurodevelopmental disorders and found none had pathogenic variants. Our findings suggest that IMPDH2 may not play a major role in dystonia.

Clinical Characteristics, Genetic Features, and Long-Term Outcome of Wilson's Disease in a Taiwanese Population: An 11-Year Follow-Up Study.

OBJECTIVE: aaWilson's disease (WD) is a rare genetic disorder of copper metabolism, and longitudinal follow-up studies are limited. We performed a retrospective analysis to determine the clinical characteristics and long-term outcomes in a large WD cohort. METHODS: aaMedical records of WD patients diagnosed from 2006-2021 at National Taiwan University Hospital were retrospectively evaluated for clinical presentations, neuroimages, genetic information, and follow-up outcomes. RESULTS: aaThe present study enrolled 123 WD patients (mean follow-up: 11.12 ± 7.41 years), including 74 patients (60.2%) with hepatic features and 49 patients (39.8%) with predominantly neuropsychiatric symptoms. Compared to the hepatic group, the neuropsychiatric group exhibited more Kayser-Fleischer rings (77.6% vs. 41.9%, p < 0.01), lower serum ceruloplasmin levels (4.9 ± 3.9 vs. 6.3 ± 3.9 mg/dL, p < 0.01), smaller total brain and subcortical gray matter volumes (p < 0.0001), and worse functional outcomes during follow-up (p = 0.0003). Among patients with available DNA samples (n = 59), the most common mutations were p.R778L (allelic frequency of 22.03%) followed by p.P992L (11.86%) and p.T935M (9.32%). Patients with at least one allele of p.R778L had a younger onset age (p = 0.04), lower ceruloplasmin levels (p < 0.01), lower serum copper levels (p = 0.03), higher percentage of the hepatic form (p = 0.03), and a better functional outcome during follow-up (p = 0.0012) compared to patients with other genetic variations. CONCLUSION: aaThe distinct clinical characteristics and long-term outcomes of patients in our cohort support the ethnic differences regarding the mutational spectrum and clinical presentations in WD.

Generation of a human induced pluripotent stem cell line NTUHi002-A from a patient with aceruloplasminemia harboring a homozygous splicing mutation c.607+1 delG in CP gene.

Aceruloplasminemia is a rare autosomal recessive disorder caused by mutations in the CP gene, encoding the copper-binding protein ceruloplasmin. A mutation in the CP gene results in brain and systemic iron overload, which is classified as a rare subtype of neurodegeneration with brain iron accumulation (NBIA). Here, we used the Sendai virus delivery system to generate induced pluripotent stem cells from peripheral blood mononuclear cells of a patient carrying the CP c.607+1 delG homozygous splicing mutation. The generated cell line retained the original genotype, expressed pluripotency markers, and differentiated into cells of the three germ layers.

Generation of induced pluripotent stem cells (IBMSi011-A) from a patient with Parkinson's disease carrying LRRK2 p.I1371V mutation.

Leucine rich repeat kinase 2 (LRRK2) is the causative gene for autosomal-dominant familial forms of Parkinson's disease (PD). Here, we generated induced pluripotent stem cells (iPSCs) from the peripheral blood mononuclear cells of a female patient with LRRK2 c.4111A > G (p.I1371V) mutation by using the Sendai-virus delivery system. The resulting iPSCs had a normal karyotype. The iPSCs also showed pluripotency confirmed by immunofluorescent staining and differentiated into the three germ layers in vivo. This cellular model will provide a platform for studying the role of LRRK2 in the disease process.

Reprogramming of a human induced pluripotent stem cell (iPSC) line (IBMSi012-A) from an early-onset Parkinson's disease patient harboring a homozygous p.D331Y mutation in the PLA2G6 gene.

A recessive mutation in PLA2G6, which is known to cause a heterogeneous neurodegenerative clinical spectrum, has recently been shown to be responsible for autosomal-recessive familial forms of Parkinson's disease (PD). Here, we generated induced pluripotent stem cells (iPSCs) from the peripheral blood mononuclear cells of a female patient with a homozygous PLA2G6 c.991G > T (p.D331Y) mutation by using the Sendai-virus delivery system. The resulting iPSCs showed pluripotency confirmed by immunofluorescent staining for pluripotency markers and differentiated into the 3 germ layers in vivo. This cellular model will provide a good resource for further pathophysiological studies of PD.

PDE8B mutation is not associated with Parkinson's disease in a Taiwanese population.

Mutations in the phosphodiesterase 8B gene (PDE8B) were recently linked to autosomal-dominant striatal degeneration clinically presenting as slowly progressive parkinsonism. PDE8B degrades cyclic adenosine monophosphate (cAMP), a second messenger involved in dopamine signaling. Dopamine deficiency is the pathognomonic feature of Parkinson's disease (PD). Few studies have explored the role of PDE8B in PD. We aim to address the genetic contribution of PDE8B in early-onset and familial PD in a Taiwanese population. Among 642 participants, we sequenced the exon containing previously reported mutations and exon-intron boundaries of PDE8B in 196 PD pedigrees without known PD-causative gene mutations, 207 patients with early-onset PD (age of onset <50 years), and 239 ethnicity-matched controls. We did not find any coding variants or previously reported mutations, suggesting that PDE8B mutations are not a common cause of familial or early-onset PD in this Taiwanese population.

Catechol-O-methyltransferase (COMT) genetic variants are associated with cognitive decline in patients with Parkinson's disease.

OBJECTIVE: Catechol-O-methyltransferase (COMT), an enzyme that catalyzes the degradation of dopamine, is necessary for both motor and cognitive functions. Few studies have examined the association between COMT variants and cognition in patients with Parkinson's disease (PD). METHODS: We assessed a cohort of 409 PD patients without dementia who were regularly followed for two years. The Unified Parkinson's Disease Rating Scale (UPDRS) and Mini-Mental State Examination (MMSE) were administered at baseline and during the follow-up. The genetic variants and haplotypes of COMT, including rs6267, rs6269, rs4633, rs4818, and rs4680, were examined. RESULTS: No association was observed between COMT genotypes and baseline cognitive function. After a mean follow-up period of 647.3 days, MMSE scores deteriorated with age. Cognitive decline correlated with age (P < 0.05) but not with the motor severity defined using UPDRS part III scores (P = 0.21). Kaplan-Meier survival analyses showed that PD patients carrying the G allele of the rs6269 variant and COMT haplotypes constituting the G allele of rs6269 showed a significantly more rapid decline in the MMSE scores over the follow-up period (log-rank test, P < 0.01). Cox proportional regression analysis adjusted for covariates revealed that among patients with PD, those carrying the high-COMT activity haplotype (G_C_C_G for rs6269, rs4633, rs4818, and rs4680) showed a high risk of cognitive decline (hazard ratio = 3.24; P = 0.02). CONCLUSION: Our findings suggest that the high-COMT activity haplotype is associated with cognitive decline in patients with PD.

Generation of 2 induced pluripotent stem cell lines derived from patients with Parkinson's disease carrying LRRK2 G2385R variant.

Leucine rich repeat kinase (LRRK2) is the most prevalent genetic cause for Parkinson's disease. LRRK2 p.G2385R is an Asian specific genetic risk factor for sporadic Parkinson's disease. We generated two induced pluripotent stem cells (iPSCs), IBMS-iPSC-018-09 and IBMS-iPSC-020-01, from the peripheral blood mononuclear cells of two patients carrying LRRK2 p.G2385R variant by using the Sendai-virus delivery system. These iPSCs had a normal karyotype and exhibited pluripotency, such as an embryonic stem cell-like morphology, expression of pluripotent markers, and capacity to differentiate into three germ layers. This cellular model will provide a platform for pathophysiological studies of neurodegeneration in Parkinson's disease.

Lack of RAB39B mutations in early-onset and familial Parkinson's disease in a Taiwanese cohort.

Loss of function mutations in RAB39B were recently linked to X-linked recessive early-onset Parkinsonism with variable degrees of intellectual dysfunction. Postmortem examination of the brain biopsy from a patient carrying the gene deletion revealed widespread α-synuclein pathology. However, subsequent analyses reported conflict results to replicate the role of RAB39B mutations in patients with early-onset Parkinsonism. The aim of this study was to address the genetic contribution of RAB39B in early-onset and familial Parkinson's disease (PD) in a Taiwanese population. Among 466 subjects, we sequenced both the exons and exon-intron boundaries of RAB39B from 235 patients with early-onset PD (age of onset <50 years), 119 probands with familial PD, and 112 ethnicity-matched control subjects. We did not find any coding variants or previously reported mutations, suggesting that RAB39B mutations are not a common cause of early-onset or familial PD in our Taiwanese population.

Depression and Catechol-O-methyltransferase (COMT) genetic variants are associated with pain in Parkinson's disease.

Pain is a distressing symptom of Parkinson disease (PD). We aim to determine whether the genetic variants of chronic pain-related genes contribute to pain in PD patients. We included 418 PD patients and evaluated pain severity on King's PD pain scale. We genotyped rs6267, rs6269, rs4633, rs4818 and rs4680 of COMT, rs6746030 of SCN9A, and rs1799971 of OPRM1. In total, 193 participants (46.2%) experienced pain. Compared to pain-free PD patients, PD patients with pain had an earlier age of onset, longer disease duration, and higher depression and motor severity (P < 0.01). The frequencies of COMT rs4680 "A" allele were higher in PD patients with pain than those without pain (46.1% vs. 31.1%, P < 0.01). Pain severity was significantly associated with disease duration (P = 0.02), and COMT rs6267 T allele (P < 0.01). We stratified PD by status of depression and the association between COMT rs6267 "GT" genotype and pain severity remained significant (P < 0.01). Furthermore, pain severity was significantly higher in participants having COMT rs4680 "GG" and "GA" genpotypes than those having "AA" genotype (P = 0.04). We concluded that depression and COMT rs4680 "GG" and "GA" genotypes and COMT rs6267 "GT" genotype contribute to pain in PD patients.

Generation of induced pluripotent stem cells from a patient with Parkinson's disease carrying LRRK2 p.I2012T mutation.

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by interactions between genetic and environmental factors. Leucine rich repeat kinase (LRRK2) is the most prevalent mutation in autosomal-dominant inheritance of PD. Here, we generated induced pluripotent stem cells (iPSCs) from the peripheral blood mononuclear cells of a female patient with p.I2012T mutation in LRRK2 gene by using the Sendai-virus delivery system. The resulting iPSCs had a normal karyotype. The iPSCs also showed pluripotency confirmed by immunofluorescent staining and differentiated into the 3 germ layers in vivo. This cellular model will provide a useful platform for further pathophysiological studies of PD.

Vitamin D receptor genetic variants and Parkinson's disease in a Taiwanese population.

Patients with Parkinson's disease (PD) have hypovitaminosis D status and genetic variants of vitamin D receptor (VDR) gene are recently shown to be associated with PD in a large-scale genome-wide association study in a Caucasian population. Few studies examined VDR genetic variants in large-scale Asian patients with PD. We therefore genotyped 6 VDR genetic variants in a total of 1492 Taiwanese subjects, including 700 patients with PD and 792 age and/or gender matched control subjects. We did not observe any significant associations between the studied genetic variants of VDR and the risk of PD. Our data suggest that genetic variations of the VDR gene did not play a major role in a Taiwanese PD population. Further studies of VDR and its interaction with serum vitamin D levels are warranted to clarify the potential role of vitamin D in PD pathogenesis.

Lack of c9orf72 repeat expansion in taiwanese patients with mixed neurodegenerative disorders.

BACKGROUND: The hexanucleotide repeat expansion in intron 1 of the C9orf72 gene is recognized as the most common genetic cause of frontotemporal dementia (FTD). There are overlapping clinical and pathological characteristics between FTD and Parkinsonism syndrome, and some FTD patients may present with Parkinsonism. The aim of this study was to analyze the hexanucleotide repeat numbers of C9orf72 gene in a mixed Taiwanese cohort with FTD, Parkinsonism syndrome, Parkinson's disease (PD), and Alzheimer's dementia (AD). METHOD: The number of hexanucleotide repeats was estimated in a total of 482 patients with mixed neurodegenerative disorders and 485 control subjects, using a two-step repeat-primed polymerase chain reaction-based genotyping strategy. The individual groups of patients included patients with Parkinsonism syndrome (n = 95), familial PD (n = 109), young-onset PD (n = 201), FTD (n = 9), sporadic AD (n = 61), and early-onset AD (n = 7). RESULTS: We did not identify any pathogenic repeats (>30 repeats) of C9orf72 in either the patients or control subjects. However, we found one young-onset PD patient and one control subject that each had an intermediate number of repeats (25 and 21 repeats, respectively). The clinical phenotype of the young-onset PD in this patient was similar to typical idiopathic PD without additional features, and the patient responded well to levodopa treatment. CONCLUSION: The repeat expansion in C9orf72 is not a common cause of PD, Parkinsonism syndrome, or dementia in our population. Further studies are needed to investigate the clinical and biological significance of intermediate repeats in C9orf72.