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This document provides consensus-based recommendations for general physicians and primary care physicians who diagnose and manage patients with mitochondrial diseases (MD). It builds on previous international guidelines, with particular emphasis on clinical management in the Australian setting. This statement was prepared by a working group of medical practitioners, nurses and allied health professionals with clinical expertise and experience in managing Australian patients with MD. As new treatments and management plans emerge, these consensus-based recommendations will continue to evolve, but current standards of care are summarised in this document.

Introduction Allogeneic hematopoietic stem cell (HSC) transplantation (allo-HSCT) is a treatment option for several monogenic diseases; however, its use is limited by the need for a matched donor and risk of HSCT-related complications. Autologous HSC gene addition does not have some of these limitations and may have similar efficacy with an improved safety profile. Ex vivo gene addition therapy using lentiviral vectors (LVV) is being evaluated in patients with transfusion-dependent β-thalassemia (TDT) using betibeglogene autotemcel (beti-cel, LentiGlobin for TDT) in the HGB-204, -205, -207, and -212 studies, sickle cell disease (SCD) using LentiGlobin for SCD in HGB-205 and -206, and cerebral adrenoleukodystrophy (CALD) using Lenti-D in ALD-102. The safety outcomes following autologous gene modified HSCT in these ongoing studies are summarized. Methods HSCs are collected using disease-appropriate procedures, then CD34+ cells are transduced with LVV encoding disease-specific therapeutic transgenes. After myeloablation with busulfan (SCD, TDT) or busulfan/cyclophosphamide (CALD), patients are infused with LVV-transduced CD34+ HSCs. Patients are followed for two years and offered participation in long term follow-up studies (LTF-303 [NCT02633943] or LTF-304 [NCT02698579]). Results Across all 6 studies, 110 patients have been treated as of most recent analyses (Table 1). Patients have been followed for 2 years follow-up. No patient experienced primary or secondary graft failure. One patient with CALD experienced disease progression and died 22 months after drug product (DP) infusion of disease complications. Two additional patients with CALD withdrew from the study after DP infusion and were referred for allo-HSCT. All other patients with CALD, TDT, and SCD remain alive. Most (107/110) patients had ≥ one grade 3 or 4 adverse event (AE) attributed to conditioning; most common AEs were cytopenia, febrile neutropenia, and stomatitis. Myelodysplastic syndrome was reported in one patient with SCD. After investigation for LVV insertion in malignant cells, the AE was assessed as not related to LentiGlobin insertion or transgene expression. AEs reported as related to the DP are shown in Table 1. There was no GVHD and no clinically relevant clonal dominance or LVV-mediated replication competent lentivirus. Summary Data from 110 patients followed for up to 5 years supports that the safety profile of gene-modified autologous HSCT does not carry the risks of GVHD, graft rejection, and long-term immunosuppression attendant to allo-HSCT. While the safety profile beyond 5-years is still being established, these data suggest that HSC gene therapy may be an acceptable therapy for patients with TDT, SCD, and CALD, particularly in patients at increased risk of complications from allo-HSCT, such as those who lack a suitable donor or are more advanced in age.

Cerebral adrenoleukodystrophy (CALD) is a rare metabolic disorder in which rapid and progressive inflammatory demyelination leads to irreversible loss of neurologic function and death. There is no approved treatment for CALD, although Lenti-D Drug Product (DP) is in development as an autologous hematopoietic stem cell (HSC) gene therapy. We have previously shown promising results from the ALD-102 clinical study of the safety and efficacy of Lenti-D DP in boys ≤17 years old with CALD; based on data from 29 patients, Lenti-D DP was generally safe and led to stabilization of disease progression. The primary efficacy endpoint in ALD-102 is the proportion of patients who are alive and free of major functional disabilities (MFD) at Month 24. The primary safety endpoint is the proportion of patients who experience acute (≥Grade 2) or chronic graft-versus-host disease (GVHD) by Month 24. ALD-102 has completed enrollment, with 32 boys having received Lenti-D DP as of April 2019. The median DP cell dose was 11.4 (min - max, 5.0 - 20.1) × 106 CD34 cells/kg; median DP vector copy number was 1.2 (min - max, 0.5 - 2.7) copies/diploid genome. Median day of neutrophil and platelet engraftment was 13.0 days (min-max, 11.0 - 41.0) and 32.0 days (min - max, 16.0 - 60.0), respectively. The median follow-up time for the cohort of 32 patients is 21.2 months (min - max, 0.0 – 60.2). Fifteen patients have completed 24 months of follow-up in ALD-102 and continue to be free of major functional disabilities (MFD) through their last follow-up in a long-term extension study. Fourteen patients remain in ALD-102; the longest follow-up among these patients is 20.4 months. Two patients were withdrawn and referred for allo-HSCT before their Month 24 visit; another experienced early and rapid disease progression while on-study resulting in MFDs and death. All other Lenti-D DP-treated patients showed stabilization of neurologic function score at their last follow-up (stable NFS was defined as NFS ≤4 without a change of >3 from baseline). There have been no reports of graft failure, GVHD, or transplant-related mortality; recorded adverse events are consistent with myeloablative conditioning. There is no evidence of replication competent lentivirus or insertional oncogenesis. Lenti-D DP appears to stabilize neurologic disease progression and continues to show favorable safety with the longest follow-up at 60.2 months. Additional follow-up is ongoing to assess durability of effects and long-term safety.

We describe a sibling pair displaying an early infantile-onset, progressive neurodegenerative phenotype, with symptoms of developmental delay and epileptic encephalopathy developing from 12 to 14 months of age. Using whole exome sequencing, compound heterozygous variants were identified in SLC5A6, which encodes the sodium-dependent multivitamin transporter (SMVT) protein. SMVT is an important transporter of the B-group vitamins biotin, pantothenate, and lipoate. The protein is ubiquitously expressed and has major roles in vitamin uptake in the digestive system, as well as transport of these vitamins across the blood–brain barrier. Pathogenicity of the identified variants was demonstrated by impaired biotin uptake of mutant SMVT. Identification of this vitamin transporter as the genetic basis of this disorder guided targeted therapeutic intervention, resulting clinically in improvement of the patient’s neurocognitive and neuromotor function. This is the second report of biallelic mutations in SLC5A6 leading to a neurodegenerative disorder due to impaired biotin, pantothenate and lipoate uptake. The genetic and phenotypic overlap of these cases confirms mutations in SLC5A6 as the genetic cause of this disease phenotype. Recognition of the genetic disorder caused by SLC5A6 mutations is essential for early diagnosis and to facilitate timely intervention by triple vitamin (biotin, pantothenate, and lipoate) replacement therapy.

Objective Adrenoleukodystrophy (ALD) is an X-linked disease caused by dysfunction of ALD protein which results in the accumulation of very-long chain fatty acids in adrenal and nervous system tissues. Cerebral ALD (CALD), affecting 35-40% of boys with ALD, is characterized by inflammatory demyelination leading to progressive loss of neurologic function and death. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has a stabilizing impact on indices of cerebral disease progression, if performed early, but can be associated with significant risks. Methods Lenti-D Drug Product (DP) is an investigational gene therapy for the treatment of CALD. Boys with CALD (≤17 years) enrolled in an open-label phase 2/3 study (Starbeam) of the safety and efficacy of Lenti-D DP underwent full myeloablation and lymphodepletion followed by infusion of autologous CD34+ cells transduced with Lenti-D lentiviral vector (elivaldogene tavalentivec). The primary efficacy endpoint is the proportion of patients who are alive and free of major functional disabilities (MFD) at Month 24. The success criterion for the primary efficacy endpoint, defined from an observational study of the natural history of CALD and supported by outcomes of allo-HSCT, will be met for the first 17 patients enrolled in the study with a point estimate of ≥76.5% (95% CI, 50.1%-93.2%) MFD-free survival at Month 24. Results As of April 2018, 29 patients received Lenti-D DP (median follow-up 34 months, min-max, 0.4-54.0). The median DP cell dose was 11 (min-max, 5.0-19.4) x106 CD34 cells/kg; median DP vector copy number was 1.2 (min-max, 0.5-2.5) copies/diploid genome. Median day of neutrophil and platelet engraftment was 13.0 (min-max, 11.0-39.0) and 30.5 (min-max, 16.0-55.0), respectively. Of the 17 patients with evaluable data at Month 24, 15 (88%, 95% CI, 63.6%-98.5%) remain alive and MFD-free with evidence of disease stabilization. The remaining 12 patients have not yet reached 24 months of follow-up; median follow-up time for this group was 4.2 months (min-max, 0.4-11.7). As of April 2018, there was no evidence of MFDs in these patients. Overall, no graft failure, GVHD, or transplant-related mortality have been reported, and there is no evidence of replication competent lentivirus or insertional oncogenesis through 54 months of follow-up. Most adverse events were consistent with myeloablative conditioning. Conclusion Lenti-D DP met the threshold for primary efficacy success in the first 17 patients to complete 24 months of follow-up. The data presented here suggest that Lenti-D DP stabilizes neurologic disease progression and may offer an alternative to allo-HSCT in patients with early cerebral disease. The study has met its enrollment target and additional follow-up is ongoing to assess durability of effects and long-term safety.

Autosomal dominant mutations in the sodium-gated potassium channel subunit gene KCNT1 have been associated with two distinct seizure syndromes, nocturnal frontal lobe epilepsy (NFLE) and malignant migrating focal seizures of infancy (MMFSI). To further explore the phenotypic spectrum associated with KCNT1, we examined individuals affected with focal epilepsy or an epileptic encephalopathy for mutations in the gene. We identified KCNT1 mutations in 12 previously unreported patients with focal epilepsy, multifocal epilepsy, cardiac arrhythmia, and in a family with sudden unexpected death in epilepsy (SUDEP), in addition to patients with NFLE and MMFSI. In contrast to the 100% penetrance so far reported for KCNT1 mutations, we observed incomplete penetrance. It is notable that we report that the one KCNT1 mutation, p.Arg398Gln, can lead to either of the two distinct phenotypes, ADNFLE or MMFSI, even within the same family. This indicates that genotype–phenotype relationships for KCNT1 mutations are not straightforward. We demonstrate that KCNT1 mutations are highly pleiotropic and are associated with phenotypes other than ADNFLE and MMFSI. KCNT1 mutations are now associated with Ohtahara syndrome, MMFSI, and nocturnal focal epilepsy. They may also be associated with multifocal epilepsy and cardiac disturbances Refereed/Peer-reviewed

BackgroundIn X-linked adrenoleukodystrophy, mutations in ABCD1 lead to loss of function of the ALD protein. Cerebral adrenoleukodystrophy is characterized by demyelination and neurodegeneration. Disease progression, which leads to loss of neurologic function and death, can be halted only with allogeneic hematopoietic stem-cell transplantation.MethodsWe enrolled boys with cerebral adrenoleukodystrophy in a single-group, open-label, phase 2-3 safety and efficacy study. Patients were required to have early-stage disease and gadolinium enhancement on magnetic resonance imaging (MRI) at screening. The investigational therapy involved infusion of autologous CD34+ cells transduced with the elivaldogene tavalentivec (Lenti-D) lentiviral vector. In this interim analysis, patients were assessed for the occurrence of graft-versus-host disease, death, and major functional disabilities, as well as changes in neurologic function and in the extent of lesions on MRI. The primary end point was being alive and having no major functional disability at 24 months after infusion.ResultsA total of 17 boys received Lenti-D gene therapy. At the time of the interim analysis, the median follow-up was 29.4 months (range, 21.6 to 42.0). All the patients had gene-marked cells after engraftment, with no evidence of preferential integration near known oncogenes or clonal outgrowth. Measurable ALD protein was observed in all the patients. No treatment-related death or graft-versus-host disease had been reported; 15 of the 17 patients (88%) were alive and free of major functional disability, with minimal clinical symptoms. One patient, who had had rapid neurologic deterioration, had died from disease progression. Another patient, who had had evidence of disease progression on MRI, had withdrawn from the study to undergo allogeneic stem-cell transplantation and later died from transplantation-related complications.ConclusionsEarly results of this study suggest that Lenti-D gene therapy may be a safe and effective alternative to allogeneic stem-cell transplantation in boys with early-stage cerebral adrenoleukodystrophy. Additional follow-up is needed to fully assess the duration of response and long-term safety. (Funded by Bluebird Bio and others; STARBEAM ClinicalTrials.gov number, NCT01896102 ; ClinicalTrialsRegister.eu number, 2011-001953-10 .).

Neuronopathic Gaucher disease type 3 (GD3) is frequent in northern Sweden, whereas GD1 is found throughout the country. In a nation-wide study, we examined neurological manifestations and clinical course in 12 patients with GD3 and 13 patients with GD1.The patients were evaluated by standardized neurological assessments. Every sixth month, the GD3 patients were rated with the modified Severity Scoring Tool. At baseline and at the 3years follow-up, patients underwent University of Pennsylvania Smell Identification Test, Montreal Cognitive Assessment and Hospital Anxiety and Depression Scale. When clinical signs were present, additional examinations were undertaken.Marked clinical heterogeneity was evident in both GD3 and GD1 groups. Several GD3 patients had a hitherto unreported rapid and repetitive dystonia-like hyperkinetic movement disorder. Most patients with GD3 have abnormalities of horizontal gaze, ataxia and focal epilepsy, some also had cognitive impairment, anxiety and hyposmia. Six GD3 patients, all homoallelic for L444P GBA1 mutations, have lived beyond 40years of age; and none has developed Parkinsonism. Two of the GD1 patients suffer from Parkinsonism; mild to complete hyposmia was present in six GD3 and five GD1 patients. Neither the group of GD3 nor GD1 patients had detectable progression of their neurological manifestations.These middle-aged and older Swedish GD3 or GD1 patients are clinically stable over time. However, we have identified unusual clinical features, discordant phenotypes and a hyperkinetic dystonia-like movement disorder which appears unique to this Swedish disease variant and expands the phenotype for GD.

Impaired sulfatide catabolism is the primary biochemical insult in patients with the inherited neurodegenerative disease, metachromatic leukodystrophy (MLD), and sulfatide elevation in body fluids is useful in the diagnostic setting. Here we used mass spectrometry to quantify fourteen species of sulfatide, in addition to the deacetylated derivative, lyso-sulfatide, using high pressure liquid chromatography-electrospray ionisation-tandem mass spectrometry in both positive and negative ion mode. A single phase extraction of 0.01 mL of MLD plasma identified all 14 sulfatide species in the positive ion mode but none in the negative ion mode. Interrogation of seven major and seven hydroxylated molecular species, as well as lyso-sulfatide, identified the C18 isoform as the most informative for MLD. The C18 produced a linear response and was below the limit of quantification ( −1 ) in control plasma with concentrations in MLD plasma ranging from 12 to 196 pmol mL −1 . Serial plasma samples from an MLD patient post-therapeutic bone marrow transplant proved similar to non-disease controls with C18 sulfatide concentrations below the limit of quantification, as did samples from three individuals with an arylsulfatase A pseudodeficiency – a population variant which appears deficient upon enzymatic assay, without manifestation of disease. These findings emphasise the utility of the C18 sulfatide species for the diagnosis of MLD and biochemical monitoring of MLD patients. Extension of this approach to a newborn screening card correctly identified an MLD patient at birth with elevated C18 sulfatide at levels almost double that present in the newborn card from his unaffected sibling, suggesting the methodology may have applicability for newborn screening.

Gaucher disease arises from mutations in the beta-glucocerebrosidase gene which encodes an enzyme required for the lysosomal catabolism of glucosylceramide. We have identified a naturally occurring mutation in the beta-glucocerebrosidase gene in sheep that leads to Gaucher disease with acute neurological symptoms. Here we have examined the clinical phenotype at birth and subsequently quantified lipids in Gaucher lamb brain, in order to characterise the disorder. Enzyme activity assessments showed that a reduction in beta-glucocerebrosidase activity to 1-5% of wild-type occurs consistently across newborn Gaucher lamb brain regions. We analyzed glucosylceramide, glucosylsphingosine, bis(monoacylglycero)phosphate and ganglioside profiles in brain, liver, and spleen, and observed 30- to 130-fold higher glucosylceramide, and 500- to 2000-fold higher glucosylsphingosine concentrations in Gaucher diseased lambs compared to wild-type. Significant increases of bis(monoacylglycero)phosphate and gangliosides [GM1, GM2, GM3] concentrations were also detected in the brain. As these glycosphingolipids are involved in many cellular events, an imbalance or disruption of the cell membrane lipid homeostasis would be expected to impair normal neuronal function. To our knowledge, this is the first detailed analysis of glycosphingolipids in various brain regions in a large animal model of neuronal disease, which permits the mechanistic investigation of lipid deregulation and their contribution to neurodegenerative process. Refereed/Peer-reviewed

Item does not contain fulltext We report siblings of consanguineous parents with an infantile-onset neurodegenerative disorder manifesting a predominant sensorimotor axonal neuropathy, optic atrophy and cognitive deficit. We used homozygosity mapping to identify an approximately 12-Mbp interval identical by descent (IBD) between the affected individuals on chromosome 3q13.13-21.1 with an LOD score of 2.31. We combined family-based whole-exome and whole-genome sequencing of parents and affected siblings and, after filtering of likely non-pathogenic variants, identified a unique missense variant in syntaxin-binding protein 5-like (STXBP5L c.3127G>A, p.Val1043Ile [CCDS43137.1]) in the IBD interval. Considering other modes of inheritance, we also found compound heterozygous variants in FMNL3 (c.114G>C, p.Phe38Leu and c.1372T>G, p.Ile458Leu [CCDS44874.1]) located on chromosome 12. STXBP5L (or Tomosyn-2) is expressed in the central and peripheral nervous system and is known to inhibit neurotransmitter release through inhibition of the formation of the SNARE complexes between synaptic vesicles and the plasma membrane. FMNL3 is expressed more widely and is a formin family protein that is involved in the regulation of cell morphology and cytoskeletal organization. The STXBP5L p.Val1043Ile variant enhanced inhibition of exocytosis in comparison with wild-type (WT) STXBP5L. Furthermore, WT STXBP5L, but not variant STXBP5L, promoted axonal outgrowth in manipulated mouse primary hippocampal neurons. However, the FMNL3 p.Phe38Leu and p.Ile458Leu variants showed minimal effects in these cells. Collectively, our clinical, genetic and molecular data suggest that the IBD variant in STXBP5L is the likely cause of the disorder.

19 F-N.m.r. studies show that N -trifluoroacetyl- d - and - l -4-fluorophenylalanine and N -trifluoroacetyl- d - and - l -phenylalanine form 1:1 inclusion complexes with cyclomaltohexaose (α-cyclodextrin) characterised by stability constants of 11.44 ±1.13, 11.40 ±1.09, 6.15 ±0.59, and 6.37 ±0.81 m −1 , respectively, in aqueous 0.1 m NaCl at pH 6.5 and 25°. Under similar conditions, the correlation time of N -trifluoroacetyl-[ 2 H 8 ]phenylalanine changed from 65 ±4 ps in the free state to 320 ±40 ps in the complex, consistent with there being little freedom of movement of the guest in the inclusion complex.