Search

Primary familial brain calcification (PFBC) is a progressive neurological disorder manifesting as bilateral brain calcifications in CT scan with symptoms as parkinsonism, dystonia, ataxia, psychiatric symptoms, etc. Recently, pathogenic variants in MYORG have been linked to autosomal recessive PFBC. This study aims to elucidate the mutational and clinical spectrum of MYORG mutations in a large cohort of Chinese PFBC patients with possible autosomal recessive or absent family history. Mutational analyses of MYORG were performed by Sanger sequencing in a cohort of 245 PFBC patients including 21 subjects from 10 families compatible with a possibly autosomal-recessive trait and 224 apparently sporadic cases. In-depth phenotyping and neuroimaging features were investigated in all patients with novel MYORG variants. Two nonsense variants (c.442C > T, p. Q148*; c.972C > A, p. Y324*) and two missense variants (c.1969G>C, p. G657R; c.2033C > G, p. P678R) of MYORG were identified in four sporadic PFBC patients, respectively. These four novel variants were absent in gnomAD, and their amino acid were highly conserved, suggesting these variants have a pathogenic impact. Patients with MYORG variants tend to display a homogeneous clinical spectrum, showing extensive brain calcification and parkinsonism, dysarthria, ataxia, or vertigo. Our findings supported the pathogenic role of MYORG variants in PFBC and identified two pathogenic variants (c.442C > T, c.972C > A), one likely pathogenic variant (c.2033C > G), and one variant of uncertain significance (c.1969G>C), further expanding the genetic and phenotypic spectrum of PFBC-MYORG.

Background: Hereditary spastic paraplegia type 5 (SPG5) is an ultra-rare neurogenetic axon-degenerative disease. The absence of treatment to prevent disease progression represents a major unmet clinical need. With a greater understanding of the pathophysiological basis of SPG5, opportunities have emerged for providing a targeted mechanistic therapy. The aims of this preliminary study were to investigate the efficacy of a PCSK9 inhibitor, Evolocumab, as a cholesterol-lowering therapy for reducing the accumulation of neurotoxic oxysterols and to evaluate the effects on axonal degeneration. Methods: This was as an open-label, evaluator-blind, single-center pilot study in which 23 SPG5 patients each received a single subcutaneous injections of 420 mg Evolocumab. Clinical data, CSF and blood were collected for analysis at enrollment and subsequent day 30. Induced pluripotent stem cells (iPSCs) were generated from the fibroblasts of a SPG5 patient to assess the mechanism of PCSK9 inhibitor’s effect on treatment. Findings: This trial is the largest sample-size prospective study among any treatment trial for SPG5. In this relatively homogeneous group of SPG5 patients (96% carried the same known nonsense mutation c.334 C>T; the median age was 34 years; disease duration was 16 years), we found that PCSK9 inhibitor significantly lowered levels of the toxic metabolite 27-hydroxycholesterol (27-OHC) in plasma (median (IQR), 589(487-644) vs. 396(348-468) ng/ml , P < 0.001). CSF 27-OHC decreased in 12 (71%) patients with a median reduction by 11% from the median 10 ng/ml before treatment to 8.3 ng/ml after treatment (P = 0.012). Most importantly, axonal degeneration, assessed by using neurofilament light (NFL) as a quantitative biomarker, receded at 30 days after single-dose Evolocumab treatment. Additionally, using iPSC-derived motor neurons, this study also showed that PCSK9 inhibitor had anti-apoptosis activity in SPG5 patients. Interpretation: The potential biological activity of cholesterol modulation for SPG5 patients, that is, alleviation of damage to axons from the effects of neurotoxic oxysterol, as well as the absence of adverse effects associated with the use of PCSK9 inhibitor therapy documented here deserves, in fact urges, full evaluation by well-designed long-term clinical trials. Trial Registration: This study is registered with ClinicalTrials.gov, number: NCT01892345. Funding Statement: This work has been supported by grants U1905210 (W.-J.C.), 81771230(W.-J.C.) and 81801130 (X.L.) from the National Natural Science Foundation of China, Joint Funds for the Innovation of Science and Technology of Fujian Province (2017Y9094) (W.-J.C.) and (2018Y9082) (N.W.), the Natural Science Foundation of Fujian Province (2019J02010) (W.-J.C.) and (2019J05076) (X.L.), the Key Clinical Specialty Discipline Construction Program of Fujian (N.W.). Declaration of Interests: All authors report no conflict of interest. Fujian medical university school of public health have received consultant fees as statistician to perform the data analysis. Ethics Approval Statement: The study protocol and informed consent procedures were approved by the institutional review board. Written informed consent was provided by the patients and their health care proxies.

Primary familial brain calcification (PFBC) is a rare neurological disorder. Mutations in five genes (SLC20A2, PDGFRB, PDGFB, XPR1, and MYORG) have been linked to PFBC. Here, we used SYBR green-based real-time quantitative polymerase chain reaction (PCR) assay and denaturing high-performance liquid chromatography analysis to detect copy number variants (CNVs) in 20 unrelated patients with PFBC, negatively sequenced for the five known genes. We identified three deletions in SLC20A2, including a large de novo full gene deletion and two exonic deletions confined to exon 2 and exon 6, respectively. Subsequent linked-read whole-genome sequencing of the patient with the large deletion showed a 1.7 Mb heterozygous deletion which removed the entire coding regions of SLC20A2 as well as 21 other genes. In the family with a deletion of exon 6, a missense variant of uncertain significance (SLC20A2: p.E267Q) also co-segregated with the disease. Functional assay showed the deletion could result in significantly impaired phosphate transport, whereas the p.E267Q variant did not. Our results confirm that deletion in SLC20A2 is a causal mechanism for PFBC and highlight the importance of functional study for classifying a rare missense variant as (likely) pathogenic.

Spinal muscular atrophy (SMA) is an autosomal recessive genetic disorder caused by survival motor neuron (SMN) protein deficiency leading the loss of motor neurons in the anterior horns of the spinal cord and brainstem. More than 95% of SMA patients are attributed to the homozygous deletion of survival motor neuron 1 (SMN1) gene, and approximately 5% are caused by compound heterozygous with a SMN1 deletion and a subtle mutation. Here, we identified a rare variant c.835-5T>G in intron 6 of SMN1 in a patient affected with type I SMA. We analyzed the functional consequences of this mutation on mRNA splicing in vitro. After transfecting pCI-SMN1, pCI-SMN2, and pCI-SMN1 c.835-5T>G minigenes into HEK293, Neuro-2a, and SHSY5Y cells, reverse transcription polymerase chain reaction (RT-PCR) was performed to compare the splicing effects of these minigenes. Finally, we found that this mutation resulted in the skipping of exon 7 in SMN1, which confirmed the genetic diagnosis of SMA.

The unbalanced voltage conditions deteriorate the performance of the harmonic detection of active power filter (APF). To address this problem, a complex LMS based method is proposed in this paper. A complex Least Mean Squares (LMS) is designed for phase-tracking. DSPOC principle is utilized to adjust the estimate of synchronous frequency. Then, the proposed method is employed to improve the harmonic detection of APF. The effectiveness of the method is confirmed through simulation results.

The effects of compensating and restraining the power system harmonics using active power filter are determined by the detection precision and its dynamic response characters. To improve both of them, a harmonic current detection algorithm based on variable forgetting factor Recursive Least-Squares algorithm is presented. The occurrence of the dynamic process is identified firstly by the judgment condition which is given by the algorithm, and then the forgetting factor is assigned dynamically, so that the convergent speed is significantly improved. The algorithm overcomes the impact of low-pass filter of traditional p-q or ip-iq algorithm, and releases the contradiction cased by the conflicting requirements of forgetting factor value between steady process and dynamic process. So it has better dynamic performance. Simulation and experiments prove the validity and feasibility of the approaches.