A mutation update for the FLNC gene in myopathies and cardiomyopathies

Filamin C (FLNC) variants are associated with cardiac and muscular phenotypes. Originally, FLNC variants were described in myofibrillar myopathy (MFM) patients. Later, high-throughput screening in cardiomyopathy cohorts determined a prominent role for FLNC in isolated hypertrophic and dilated cardiomyopathies (HCM and DCM). FLNC variants are now among the more prevalent causes of genetic DCM. FLNC-associated DCM is associated with a malignant clinical course and a high risk of sudden cardiac death. The clinical spectrum of FLNC suggests different pathomechanisms related to variant types and their location in the gene. The appropriate functioning of FLNC is crucial for structural integrity and cell signaling of the sarcomere. The secondary protein structure of FLNC is critical to ensure this function. Truncating variants with subsequent haploinsufficiency are associated with DCM and cardiac arrhythmias. Interference with the dimerization and folding of the protein leads to aggregate formation detrim

Heterozygous missense variants of LMX1A lead to nonsyndromic hearing impairment and vestibular dysfunction

Unraveling the causes and pathomechanisms of progressive disorders is essential for the development of therapeutic strategies. Here, we identified heterozygous pathogenic missense variants of LMX1A in two families of Dutch origin with progressive nonsyndromic hearing impairment (HI), using whole exome sequencing. One variant, c.721G > C (p.Val241Leu), occurred de novo and is predicted to affect the homeodomain of LMX1A, which is essential for DNA binding. The second variant, c.290G > C (p.Cys97Ser), predicted to affect a zinc-binding residue of the second LIM domain that is involved in protein–protein interactions. Bi-allelic deleterious variants of Lmx1a are associated with a complex phenotype in mice, including deafness and vestibular defects, due to arrest of inner ear development. Although Lmx1a mouse mutants demonstrate neurological, skeletal, pigmentation and reproductive system abnormalities, no syndromic features were present in the participating subjects of either family. LMX1A has previously been suggested as a candidate gene for intellectual disability, but our data do not support this, as affected subjects displayed normal cognition. Large variability was observed in the age of onset (a)symmetry, severity and progression rate of HI. About half of the affected individuals displayed vestibular dysfunction and experienced symptoms thereof. The late-onset progressive phenotype and the absence of cochleovestibular malformations on computed tomography scans indicate that heterozygous defects of LMX1A do not result in severe developmental abnormalities in humans. We propose that a single LMX1A wild-type copy is sufficient for normal development but insufficient for maintenance of cochleovestibular function. Alternatively, minor cochleovestibular developmental abnormalities could eventually lead to the progressive phenotype seen in the families

Improving fatigue assessment in immune-mediated neuropathies : the modified Rasch-built fatigue severity scale

Fatigue is a major disabling complaint in patients with immune-mediated neuropathies (IN). The 9-item fatigue severity scale (FSS) has been used to assess fatigue in these conditions, despite having limitations due to its classic ordinal construct. The aim was to improve fatigue assessment in IN through evaluation of the FSS using a modern clinimetric approach [Rasch unidimensional measurement model (RUMM2020)]. Included were 192 stable patients with Guillain-Barr\ue9 syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) or polyneuropathy associated with monoclonal gammopathy of undetermined significance (MGUSP). The obtained FSS data were exposed to RUMM2020 model to investigate whether this scale would meet its expectations. Also, reliability and validity studies were performed. The original FSS did not meet the Rasch model expectations, primarily based on two misfitting items, one of these also showing bias towards the factor 'walking independent.' After removing these two items and collapsing the original 7-point Likert options to 4-point response categories for the remaining items, we succeeded in constructing a 7-item Rasch-built scale that fulfilled all requirements of unidimensionality, linearity, and rating scale model. Good reliability and validity were also obtained for the modified FSS scale. In conclusion, a 7-item linearly weighted Rasch-built modified FSS is presented for more proper assessment of fatigue in future studies in patients with immune-mediated neuropathies

Revised normative values for grip strength with the Jamar dynamometer

The Jamar dynamometer has been widely used in various chronic illnesses and has demonstrated its strength as a potential prognostic indicator. Various stratified normative values have been published using different methodologies, leading to conflicting results. No study used statistical techniques considering the non-Gaussian distribution of the obtained grip strength (GS) values. Jamar GS was assessed in 720 healthy participants, subdivided into seven age decade groups consisting of at least 50 men and 50 women each. Normative values (median and fifth values) were calculated using quantile regressions with restricted cubic spline functions on age. Possible confounding personal factors (hand dominance, length, weight, hobby, and job categorization) were examined. Clinically applicable revised normative values for the Jamar dynamometer, stratified for age and gender, are presented. Hand dominance had no influence. Other personal factors only minimally influenced final values. This study provides revised normative GS values for the Jamar dynamometer

Revised normative values for grip strength with the Jamar dynamometer

The Jamar dynamometer has been widely used in various chronic illnesses and has demonstrated its strength as a potential prognostic indicator. Various stratified normative values have been published using different methodologies, leading to conflicting results. No study used statistical techniques considering the non-Gaussian distribution of the obtained grip strength (GS) values. Jamar GS was assessed in 720 healthy participants, subdivided into seven age decade groups consisting of at least 50 men and 50 women each. Normative values (median and fifth values) were calculated using quantile regressions with restricted cubic spline functions on age. Possible confounding personal factors (hand dominance, length, weight, hobby, and job categorization) were examined. Clinically applicable revised normative values for the Jamar dynamometer, stratified for age and gender, are presented. Hand dominance had no influence. Other personal factors only minimally influenced final values. This study provides revised normative GS values for the Jamar dynamometer

Does ability to walk reflect general functionality in inflammatory neuropathies?

The "ability to walk" is considered a benchmark for good clinical recovery and prognosis, particularly in patients with Guillain-Barre syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). However, it has never been determined whether being "able to walk" represents general functionality. The purpose of this study was to examine whether the ability to walk outside independently reflects general functional improvement in patients with GBS, CIDP, and gammopathy-related neuropathy (MGUSP). A total of 137 patients with newly diagnosed (or relapsing) GBS (55), CIDP (59), and MGUSP (23) were serially examined (1-year). Predefined arbitrary cut-offs (so-called patients' Functional-Acceptable-Clinical-Thresholds [FACTs]) were taken at the 50th, 75th, and 90th percentile of the Inflammatory-Rasch-built-Overall-Disability-Scale (I-RODS((c)) ). We determined the proportion of patients able to walk outside independently that reached the postulated cut-offs. A mean total of 85%, 39%, and 12% of all patients able to walk reached 50th, 75th, and 90th percentile thresholds, respectively. These findings were not neuropathy type related. Our findings show that assessing only one construct of functionality (e.g., walking ability) does not reflect the full scope of daily/social functional deficits perceived by patients. The ability to walk shows a patient is doing better, but not necessarily doing well. The I-RODS((c)) bypasses these limitations

Outcome measures in MMN revisited : Further improvement needed

The objectives of this study were to provide an overview of the outcome measures (OMs) applied in clinical trials in multifocal motor neuropathy (MMN) and to determine the responsiveness of a core set of selected OMs as part of the peripheral neuropathy outcome measures standardization (PeriNomS) study. The following OMs were serially applied in 26 patients with newly diagnosed or relapsing MMN, receiving intravenous immunoglobulin (assessments: T0/T3/T12 months): 14 muscle pairs MRC (Medical Research Council) scale, the Neuropathy Impairment Scale motor-subset, a self-evaluation scale, grip strength, and MMN-RODS\ua9 (Rasch-built overall disability scale). All data, except the grip strength, were subjected to Rasch analyses before determining responsiveness. For grip strength, responsiveness was examined using a combined anchor- (SF-36 question-2) and distribution-based ( 7 SD) minimum clinically important difference (MCID) techniques, determining the proportion of patients exceeding both the identified cut-offs. For the remaining scales, the magnitude of change for each patient on each scale was determined using the MCID related to the individual SE (responder definition: MCID-SE 65 1.96). Overall, a great assortment of measures has been used in MMN trials with different responsiveness definitions. For the selected OMs, responsiveness was poor and only seen in one fourth to one third of the patients, the grip strength being more responsive. Despite the efforts taken to standardize outcome assessment, further clinimetric responsiveness studies are needed in MMN

Metabolic Profiling Associates with Disease Severity in Nonischemic Dilated Cardiomyopathy

Contains fulltext : 218291.pdf (Publisher’s version ) (Open Access)BACKGROUND: Metabolomic profiling may have diagnostic and prognostic value in heart failure. This study investigated whether targeted blood and urine metabolomics reflects disease severity in patients with nonischemic dilated cardiomyopathy (DCM) and compared its incremental value on top of N-terminal prohormone of brain natriuretic peptide (NT-proBNP). METHODS AND RESULTS: A total of 149 metabolites were measured in plasma and urine samples of 273 patients with DCM and with varying stages of disease (patients with DCM and normal left ventricular reverse remodeling, n=70; asymptomatic DCM, n=72; and symptomatic DCM, n=131). Acylcarnitines, sialic acid and glutamic acid are the most distinctive metabolites associated with disease severity, as repeatedly revealed by unibiomarker linear regression, sparse partial least squares discriminant analysis, random forest, and conditional random forest analyses. However, the absolute difference in the metabolic profile among groups was marginal. A decision-tree model based on the top metabolites did not surpass NT-proBNP in classifying stages. However, a combination of NT-proBNP and the top metabolites improved the decision tree to distinguish patients with DCM and left ventricular reverse remodeling from symptomatic DCM (area under the curve 0.813 +/- 0.138 vs 0.739 +/- 0.114; P=0.02). CONCLUSION: Functional cardiac recovery is reflected in metabolomics. These alterations reveal potential alternative treatment targets in advanced symptomatic DCM. The metabolic profile can complement NT-proBNP in determining disease severity in nonischemic DCM