Modified Delphi procedure-based expert consensus on endpoints for an international disease registry for Metachromatic Leukodystrophy:The European Metachromatic Leukodystrophy initiative (MLDi)

BACKGROUND: Metachromatic Leukodystrophy (MLD) is a rare lysosomal disorder. Patients suffer from relentless neurological deterioration leading to premature death. Recently, new treatment modalities, including gene therapy and enzyme replacement therapy, have been developed. Those advances increase the need for high-quality research infrastructure to adequately compare treatments, execute post-marketing surveillance, and perform health technology assessments (HTA). To facilitate this, a group of MLD experts started the MLD initiative (MLDi) and initiated an academia-led European MLD registry: the MLDi. An expert-based consensus procedure, namely a modified Delphi procedure, was used to determine the data elements required to answer academic, regulatory, and HTA research questions. RESULTS: Three distinct sets of data elements were defined by the 13-member expert panel. The minimal set (n = 13) contained demographics and basic disease characteristics. The core set (n = 55) included functional status scores in terms of motor, manual, speech and eating abilities, and causal and supportive treatment characteristics. Health-related quality of life scores were included that were also deemed necessary for HTA. The optional set (n = 31) contained additional clinical aspects, such as findings at neurological examination, detailed motor function, presence of peripheral neuropathy, gall bladder involvement and micturition. CONCLUSION: Using a modified Delphi procedure with physicians from the main expert centers, consensus was reached on a core set of data that can be collected retrospectively and prospectively. With this consensus-based approach, an important step towards harmonization was made. This unique dataset will support knowledge about the disease and facilitate regulatory requirements related to the launch of new treatments. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13023-022-02189-w

Genetic and phenotypic spectrum associated with IFIH1 gain-of-function

IFIH1 gain-of-function has been reported as a cause of a type I interferonopathy encompassing a spectrum of autoinflammatory phenotypes including Aicardi–Goutières syndrome and Singleton Merten syndrome. Ascertaining patients through a European and North American collaboration, we set out to describe the molecular, clinical and interferon status of a cohort of individuals with pathogenic heterozygous mutations in IFIH1. We identified 74 individuals from 51 families segregating a total of 27 likely pathogenic mutations in IFIH1. Ten adult individuals, 13.5% of all mutation carriers, were clinically asymptomatic (with seven of these aged over 50 years). All mutations were associated with enhanced type I interferon signaling, including six variants (22%) which were predicted as benign according to multiple in silico pathogenicity programs. The identified mutations cluster close to the ATP binding region of the protein. These data confirm variable expression and nonpenetrance as important characteristics of the IFIH1 genotype, a consistent association with enhanced type I interferon signaling, and a common mutational mechanism involving increased RNA binding affinity or decreased efficiency of ATP hydrolysis and filament disassembly rate

Modified Delphi procedure-based expert consensus on endpoints for an international disease registry for Metachromatic Leukodystrophy: The European Metachromatic Leukodystrophy initiative (MLDi)

BACKGROUND: Metachromatic Leukodystrophy (MLD) is a rare lysosomal disorder. Patients suffer from relentless neurological deterioration leading to premature death. Recently, new treatment modalities, including gene therapy and enzyme replacement therapy, have been developed. Those advances increase the need for high-quality research infrastructure to adequately compare treatments, execute post-marketing surveillance, and perform health technology assessments (HTA). To facilitate this, a group of MLD experts started the MLD initiative (MLDi) and initiated an academia-led European MLD registry: the MLDi. An expert-based consensus procedure, namely a modified Delphi procedure, was used to determine the data elements required to answer academic, regulatory, and HTA research questions. RESULTS: Three distinct sets of data elements were defined by the 13-member expert panel. The minimal set (n = 13) contained demographics and basic disease characteristics. The core set (n = 55) included functional status scores in terms of motor, manual, speech and eating abilities, and causal and supportive treatment characteristics. Health-related quality of life scores were included that were also deemed necessary for HTA. The optional set (n = 31) contained additional clinical aspects, such as findings at neurological examination, detailed motor function, presence of peripheral neuropathy, gall bladder involvement and micturition. CONCLUSION: Using a modified Delphi procedure with physicians from the main expert centers, consensus was reached on a core set of data that can be collected retrospectively and prospectively. With this consensus-based approach, an important step towards harmonization was made. This unique dataset will support knowledge about the disease and facilitate regulatory requirements related to the launch of new treatments

Leukoencephalopathy with thalamus and brainstem involvement and high lactate 'LTBL' caused by EARS2 mutations

In the large group of genetically undetermined infantile-onset mitochondrial encephalopathies, multiple defects of mitochondrial DNA-related respiratory-chain complexes constitute a frequent biochemical signature. In order to identify responsible genes, we used exome-next-generation sequencing in a selected cohort of patients with this biochemical signature. In an isolated patient, we found two mutant alleles for EARS2, the gene encoding mitochondrial glutamyl-tRNA synthetase. The brain magnetic resonance imaging of this patient was hallmarked by extensive symmetrical cerebral white matter abnormalities sparing the periventricular rim and symmetrical signal abnormalities of the thalami, midbrain, pons, medulla oblongata and cerebellar white matter. Proton magnetic resonance spectroscopy showed increased lactate. We matched this magnetic resonance imaging pattern with that of a cohort of 11 previously selected unrelated cases. We found mutations in the EARS2 gene in all. Subsequent detailed clinical and magnetic resonance imaging based phenotyping revealed two distinct groups: mild and severe. All 12 patients shared an infantile onset and rapidly progressive disease with severe magnetic resonance imaging abnormalities and increased lactate in body fluids and proton magnetic resonance spectroscopy. Patients in the 'mild' group partially recovered and regained milestones in the following years with striking magnetic resonance imaging improvement and declining lactate levels, whereas those of the 'severe' group were characterized by clinical stagnation, brain atrophy on magnetic resonance imaging and persistent lactate increases. This new neurological disease, early-onset leukoencephalopathy with thalamus and brainstem involvement and high lactate, is hallmarked by unique magnetic resonance imaging features, defined by a peculiar biphasic clinical course and caused by mutations in a single gene, EARS2, expanding the list of medically relevant defects of mitochondrial DNA translation. © 2012 The Author

Modified Delphi procedure-based expert consensus on endpoints for an international disease registry for Metachromatic Leukodystrophy: The European Metachromatic Leukodystrophy initiative (MLDi)

BACKGROUND: Metachromatic Leukodystrophy (MLD) is a rare lysosomal disorder. Patients suffer from relentless neurological deterioration leading to premature death. Recently, new treatment modalities, including gene therapy and enzyme replacement therapy, have been developed. Those advances increase the need for high-quality research infrastructure to adequately compare treatments, execute post-marketing surveillance, and perform health technology assessments (HTA). To facilitate this, a group of MLD experts started the MLD initiative (MLDi) and initiated an academia-led European MLD registry: the MLDi. An expert-based consensus procedure, namely a modified Delphi procedure, was used to determine the data elements required to answer academic, regulatory, and HTA research questions. RESULTS: Three distinct sets of data elements were defined by the 13-member expert panel. The minimal set (n = 13) contained demographics and basic disease characteristics. The core set (n = 55) included functional status scores in terms of motor, manual, speech and eating abilities, and causal and supportive treatment characteristics. Health-related quality of life scores were included that were also deemed necessary for HTA. The optional set (n = 31) contained additional clinical aspects, such as findings at neurological examination, detailed motor function, presence of peripheral neuropathy, gall bladder involvement and micturition. CONCLUSION: Using a modified Delphi procedure with physicians from the main expert centers, consensus was reached on a core set of data that can be collected retrospectively and prospectively. With this consensus-based approach, an important step towards harmonization was made. This unique dataset will support knowledge about the disease and facilitate regulatory requirements related to the launch of new treatments

Synthesis of water-dispersible photoluminescent silicon nanoparticles and their use in biological fluorescent imaging

Water-dispersible silicon nanoparticles (Si-NPs) are desirable for applications in biological techniques. A simplified method to synthesize such particles is reported here. The resulting Si-NPs are water-dispersible and luminescent. Under the excitation of UV light, the Si-NPs emit strong red light with a peak maximum at 606 nm and a quantum yield of 6%. They are highly stable, and remain so over several weeks. Fourier Transform Infrared (FTIR) spectroscopy shows a visible Si–CH2 scissoring vibration mode. Furthermore, the surface chemical bondings were confirmed by X-ray photoelectron spectroscopy (XPS). In the Si2p and C1s core levels, Si–C components are observed. The diameters of the synthesized Si-NPS as measured by atomic force microscope (AFM) are approximately 5 nm. Furthermore, the nanoparticles can be taken up by cultured cells. Fluorescence images of Si-NPs within MCF-7 human breast cancer cells show they are distributed throughout the cell tissue

Defective removal of ribonucleotides from DNA promotes systemic autoimmunity

Genome integrity is continuously challenged by the DNA damage that arises during normal cell metabolism. Biallelic mutations in the genes encoding the genome surveillance enzyme ribonuclease H2 (RNase H2) cause Aicardi-Goutières syndrome (AGS), a pediatric disorder that shares features with the autoimmune disease systemic lupus erythematosus (SLE). Here we determined that heterozygous parents of AGS patients exhibit an intermediate autoimmune phenotype and demonstrated a genetic association between rare RNASEH2 sequence variants and SLE. Evaluation of patient cells revealed that SLE- and AGS-associated mutations impair RNase H2 function and result in accumulation of ribonucleotides in genomic DNA. The ensuing chronic low level of DNA damage triggered a DNA damage response characterized by constitutive p53 phosphorylation and senescence. Patient fibroblasts exhibited constitutive upregulation of IFN-stimulated genes and an enhanced type I IFN response to the immunostimulatory nucleic acid polyinosinic:polycytidylic acid and UV light irradiation, linking RNase H2 deficiency to potentiation of innate immune signaling. Moreover, UV-induced cyclobutane pyrimidine dimer formation was markedly enhanced in ribonucleotide-containing DNA, providing a mechanism for photosensitivity in RNase H2–associated SLE. Collectively, our findings implicate RNase H2 in the pathogenesis of SLE and suggest a role of DNA damage–associated pathways in the initiation of autoimmunity

PIGN encephalopathy: Characterizing the epileptology

International audienceOBJECTIVE: Epilepsy is common in patients with PIGN diseases due to biallelic variants; however, limited epilepsy phenotyping data have been reported. We describe the epileptology of PIGN encephalopathy. METHODS: We recruited patients with epilepsy due to biallelic PIGN variants and obtained clinical data regarding age at seizure onset/offset and semiology, development, medical history, examination, electroencephalogram, neuroimaging, and treatment. Seizure and epilepsy types were classified. RESULTS: Twenty six patients (13 female) from 26 families were identified, with mean age 7 years (range = 1 month to 21 years; three deceased). Abnormal development at seizure onset was present in 25 of 26. Developmental outcome was most frequently profound (14/26) or severe (11/26). Patients presented with focal motor (12/26), unknown onset motor (5/26), focal impaired awareness (1/26), absence (2/26), myoclonic (2/26), myoclonic-atonic (1/26), and generalized tonic-clonic (2/26) seizures. Twenty of 26 were classified as developmental and epileptic encephalopathy (DEE): 55% (11/20) focal DEE, 30% (6/20) generalized DEE, and 15% (3/20) combined DEE. Six had intellectual disability and epilepsy (ID+E): two generalized and four focal epilepsy. Mean age at seizure onset was 13 months (birth to 10 years), with a lower mean onset in DEE (7 months) compared with ID+E (33 months). Patients with DEE had drug-resistant epilepsy, compared to 4/6 ID+E patients, who were seizure-free. Hyperkinetic movement disorder occurred in 13 of 26 patients. Twenty-seven of 34 variants were novel. Variants were truncating (n = 7), intronic and predicted to affect splicing (n = 7), and missense or inframe indels (n = 20, of which 11 were predicted to affect splicing). Seven variants were recurrent, including p.Leu311Trp in 10 unrelated patients, nine with generalized seizures, accounting for nine of the 11 patients in this cohort with generalized seizures. SIGNIFICANCE: PIGN encephalopathy is a complex autosomal recessive disorder associated with a wide spectrum of epilepsy phenotypes, typically with substantial profound to severe developmental impairment

PIGN encephalopathy: Characterizing the epileptology

International audienceOBJECTIVE: Epilepsy is common in patients with PIGN diseases due to biallelic variants; however, limited epilepsy phenotyping data have been reported. We describe the epileptology of PIGN encephalopathy. METHODS: We recruited patients with epilepsy due to biallelic PIGN variants and obtained clinical data regarding age at seizure onset/offset and semiology, development, medical history, examination, electroencephalogram, neuroimaging, and treatment. Seizure and epilepsy types were classified. RESULTS: Twenty six patients (13 female) from 26 families were identified, with mean age 7 years (range = 1 month to 21 years; three deceased). Abnormal development at seizure onset was present in 25 of 26. Developmental outcome was most frequently profound (14/26) or severe (11/26). Patients presented with focal motor (12/26), unknown onset motor (5/26), focal impaired awareness (1/26), absence (2/26), myoclonic (2/26), myoclonic-atonic (1/26), and generalized tonic-clonic (2/26) seizures. Twenty of 26 were classified as developmental and epileptic encephalopathy (DEE): 55% (11/20) focal DEE, 30% (6/20) generalized DEE, and 15% (3/20) combined DEE. Six had intellectual disability and epilepsy (ID+E): two generalized and four focal epilepsy. Mean age at seizure onset was 13 months (birth to 10 years), with a lower mean onset in DEE (7 months) compared with ID+E (33 months). Patients with DEE had drug-resistant epilepsy, compared to 4/6 ID+E patients, who were seizure-free. Hyperkinetic movement disorder occurred in 13 of 26 patients. Twenty-seven of 34 variants were novel. Variants were truncating (n = 7), intronic and predicted to affect splicing (n = 7), and missense or inframe indels (n = 20, of which 11 were predicted to affect splicing). Seven variants were recurrent, including p.Leu311Trp in 10 unrelated patients, nine with generalized seizures, accounting for nine of the 11 patients in this cohort with generalized seizures. SIGNIFICANCE: PIGN encephalopathy is a complex autosomal recessive disorder associated with a wide spectrum of epilepsy phenotypes, typically with substantial profound to severe developmental impairment