PDXKmutations cause polyneuropathy responsive to pyridoxal 5′‐phosphate supplementation (original) (raw)
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PDXK Mutations Cause Polyneuropathy Responsive to Pyridoxal 5 0 -Phosphate Supplementation
PDXK Mutations Cause Polyneuropathy Responsive to Pyridoxal 50 -Phosphate Supplementation, 2019
Objective: To identify disease-causing variants in autosomal recessive axonal polyneuropathy with optic atrophy and provide targeted replacement therapy. Methods: We performed genome-wide sequencing, homozygosity mapping, and segregation analysis for novel disease-causing gene discovery. We used circular dichroism to show secondary structure changes and isothermal titration calorimetry to investigate the impact of variants on adenosine triphosphate (ATP) binding. Pathogenicity was further supported by enzymatic assays and mass spectroscopy on recombinant protein, patient-derived fibroblasts, plasma, and erythrocytes. Response to supplementation was measured with clinical validated rating scales, electrophysiology, and biochemical quantification. Results: We identified biallelic mutations in PDXK in 5 individuals from 2 unrelated families with primary axonal polyneuropathy and optic atrophy. The natural history of this disorder suggests that untreated, affected individuals become wheelchair-bound and blind. We identified conformational rearrangement in the mutant enzyme around the ATPbinding pocket. Low PDXK ATP binding resulted in decreased erythrocyte PDXK activity and low pyridoxal 50 - phosphate (PLP) concentrations. We rescued the clinical and biochemical profile with PLP supplementation in 1 family, improvement in power, pain, and fatigue contributing to patients regaining their ability to walk independently during the first year of PLP normalization. Interpretation: We show that mutations in PDXK cause autosomal recessive axonal peripheral polyneuropathy leading to disease via reduced PDXK enzymatic activity and low PLP. We show that the biochemical profile can be rescued with PLP supplementation associated with clinical improvement. As B6 is a cofactor in diverse essential biological pathways, our findings may have direct implications for neuropathies of unknown etiology characterized by reduced PLP levels.
Parkinsonism & Related Disorders, 2014
Background: Recent reports suggest increased frequency of peripheral neuropathy (PN) in Parkinson's disease (PD) patients on levodopa compared with age-matched controls particularly during continuous levodopa delivery by intestinal infusion (CLDII). The aim of this study is to compare frequency, clinical features, and outcome of PN in PD patients undergoing different therapeutic regimens. Methods: Three groups of consecutive PD patients, 50 on intestinal levodopa (CLDII), 50 on oral levodopa (O-LD) and 50 on other dopaminergic treatment (ODT), were enrolled in this study to assess frequency of PN using clinical and neurophysiological parameters. A biochemical study of all PN patients was performed. Results: Frequency of PN of no evident cause was 28% in CLDII, 20% in O-LD, and 6% in ODT patients. Clinically, 71% of CLDII patients and all O-LD and ODT PN patients displayed a subacute sensory PN. In contrast, 29% of CLDII patients presented acute motor PN. Levodopa daily dose, vitamin B12 (VB12) and homocysteine (hcy) levels differed significantly in patients with PN compared to patients without PN. Conclusions: Our findings support the relationship between levodopa and PN and confirm that an imbalance in VB12/hcy may be a key pathogenic factor. We suggest two different, possibly overlapping mechanisms of PN in patients on CDLII: axonal degeneration due to vitamin deficiency and inflammatory damage. Whether inflammatory damage is triggered by vitamin deficiency and/or by modifications in the intestinal micro-environment should be further explored. Proper vitamin supplementation may prevent peripheral damage in most cases.
Selected Risk Nutritional Factors for Chemotherapy-Induced Polyneuropathy
Nutrients
The present study seeks to identify the nutritional risk factors involved in the development of neuropathies induced by chemotherapeutic treatments. Unlike the gastrointestinal or hematological adverse effects of chemotherapy there is no protective treatment strategy for polyneuropathy. The aim of this study was to find possible deficiencies in nutritional factors, which can be used for supplementation in the future for prevention of chemotherapy-induced neuropathy development. We analyzed 70 patients undergoing paclitaxel chemotherapy and evaluated the risk factors involved in chemotherapy-induced peripheral neuropathy (CIPN). Several risk factors were considered in the development of CIPN, including deficiency of vitamin B1, B6, and D and fatty acids. The occurrence of CIPN complication in 60% cases was observed. We found significant differences in vitamin D and saturated fatty acid concentration. Vitamin D levels in the group without CIPN were estimated to be 38.2 (24.95, 47.63) nmol/L, whereas in the group with CIPN it was determined to be 25.6 (19.7, 32.55) nmol/L, p = 0.008. The level of total saturated fatty acids in the group without CIPN was of 32.613 Area % (31.322; 36.262), whereas in the group with CIPN it was of 34.209 Area % (32.86; 39.386), p = 0.01. The obtained results suggest a diet lower in saturated fatty acid content during chemotherapy. The most significant finding was that supplementation of vitamin D before chemotherapy could be an efficient neuroprotective in CIPN prophylaxis, as significantly lower levels 25OH derivative of vitamin D were observed in the CIPN group throughout the study period.
Neuromuscular Disorders, 2020
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Peripheral neuropathy in 30 duodopa patients with vitamins B supplementation
Acta Neurologica Scandinavica, 2017
Peripheral neuropathy (PN) is a significant concern and potential cause of withdrawal in patients with Parkinson's disease (PD) treated with Levodopa/Carbidopa Intestinal Gel (LCIG) infusion. Vitamin B deficiency and/or hyperhomocysteinemia levodopa-related are considered possible causative factors. In this study, we evaluated PN incidence in LCIG-PD patients treated since the beginning of infusion with vitamins B supplementation. Materials & Methods: In this prospective open-label pilot study, 30 consecutive patients with PD on LCIG infusion were evaluated with clinical, neurophysiological, and biochemical assessments for a mean follow-up of 42.4 months (range 24-72). All evaluations were repeated every 6 months. Results: At baseline, 21 of 30 presented no signs or symptoms of PN, and 9 of 30 had pre-existing chronic PN. In whole population, a progressive worsening in nerve conduction studies of sural sensory and peroneal motor nerves was observed during the long-term follow-up. 4 of 21 patients, with normal clinical, electrophysiological assessment at baseline, developed distal symmetrical axonal polyneuropathy that remained asymptomatic during the long-term follow-up. Patients with pre-existing PN (9 of 30) showed a mild worsening of electrophysiological features during the period of observation. In none PN was cause of discontinuation of LCIG therapy. No incident cases of acute-subacute PN were documented. No correlation was found with age, sex, Levodopa dosage, duration of levodopa exposure, and homocysteine plasma levels. Conclusion: In this consecutive series of 30 patients with PD on LCIG infusion, with early and continuous vitamins B integration, we observed a low rate (19%) of new onset peripheral polyneuropathy that remained stable after long-term follow-up. Larger studies, controlled, with blinded evaluation, are needed to confirm these findings.
Neuro-Oncology, 2012
Peripheral neuropathies induced by chemotherapy (CIPN) are an increasingly frequent problem. Contrary to hematologic adverse effects, which can be treated with hematopoetic growth factors, neither prophylaxis nor specific treatment is available, and only symptomatic treatment can be offered. Neurotoxic drugs are becoming a major dose-limiting factor. The epidemiology is still unclear. Several drug-dependent pathogenetic mechanisms exist. CIPN are predominately sensory, lengthdependent neuropathies that develop after a typical cumulative dose. Usually, the appearance of CIPN is dose dependent, although in at least 2 drugs (oxaliplatin and taxanes), immediate toxic effects occur. The most frequent substances causing CIPN are platin compounds, vinka alkaloids, taxanes, and bortezomib and thalidomide. The role of synergistic neurotoxicity caused by previously given chemotherapies and concomitant chemotherapies and the role pre-existent neuropathy on the development of a CIPN is not clear. As the number of long-term cancer survivors increases and a new focus on long-term effects of chemotherapyinduced neuropathies emerge, concepts of rehabilitation need to be implemented to improve the patients' functions and quality of life.