Background
Natural history studies in neuromuscular disorders are vital to understand the disease evolution and to find sensitive outcome measures. We performed a longitudinal assessment of ...quantitative magnetic resonance imaging (MRI) and phosphorus magnetic resonance spectroscopy (31P MRS) outcome measures and evaluated their relationship with function in lower limb skeletal muscle of dysferlinopathy patients.
Methods
Quantitative MRI/31P MRS data were obtained at 3 T in two different sites in 54 patients and 12 controls, at baseline, and three annual follow‐up visits. Fat fraction (FF), contractile cross‐sectional area (cCSA), and muscle water T2 in both global leg and thigh segments and individual muscles and 31P MRS indices in the anterior leg compartment were assessed. Analysis included comparisons between patients and controls, assessments of annual changes using a linear mixed model, standardized response means (SRM), and correlations between MRI and 31P MRS markers and functional markers.
Results
Posterior muscles in thigh and leg showed the highest FF values. FF at baseline was highly heterogeneous across patients. In ambulant patients, median annual increases in global thigh and leg segment FF values were 4.1% and 3.0%, respectively (P < 0.001). After 3 years, global thigh and leg FF increases were 9.6% and 8.4%, respectively (P < 0.001). SRM values for global thigh FF were over 0.8 for all years. Vastus lateralis muscle showed the highest SRM values across all time points. cCSA decreased significantly after 3 years with median values of 11.0% and 12.8% in global thigh and global leg, respectively (P < 0.001). Water T2 values in ambulant patients were significantly increased, as compared with control values (P < 0.001). The highest water T2 values were found in the anterior part of thigh and leg. Almost all 31P MRS indices were significantly different in patients as compared with controls (P < 0.006), except for pHw, and remained, similar as to water T2, abnormal for the whole study duration. Global thigh water T2 at baseline was significantly correlated to the change in FF after 3 years (ρ = 0.52, P < 0.001). There was also a significant relationship between the change in functional score and change in FF after 3 years in ambulant patients (ρ = −0.55, P = 0.010).
Conclusions
This multi‐centre study has shown that quantitative MRI/31P MRS measurements in a heterogeneous group of dysferlinopathy patients can measure significant changes over the course of 3 years. These data can be used as reference values in view of future clinical trials in dysferlinopathy or comparisons with quantitative MRI/S data obtained in other limb‐girdle muscular dystrophy subtypes.
Background
Water T2 (T2H2O) mapping is increasingly being used in muscular dystrophies to assess active muscle damage. It has been suggested as a surrogate outcome measure for clinical trials. Here, ...we investigated the prognostic utility of T2H2O to identify changes in muscle function over time in limb girdle muscular dystrophies.
Methods
Patients with genetically confirmed dysferlinopathy were assessed as part of the Jain Foundation Clinical Outcomes Study in dysferlinopathy. The cohort included 18 patients from two sites, both equipped with 3‐tesla magnetic resonance imaging (MRI) systems from the same vendor. T2H2O value was defined as higher or lower than the median in each muscle bilaterally. The degree of deterioration on four functional tests over 3 years was assessed in a linear model against covariates of high or low T2H2O at baseline, age, disease duration, and baseline function.
Results
A higher T2H2O at baseline significantly correlated with a greater decline on functional tests in 21 out of 35 muscles and was never associated with slower decline. Higher baseline T2H2O in adductor magnus, vastus intermedius, vastus lateralis, and vastus medialis were the most sensitive, being associated bilaterally with greater decline in multiple timed tests. Patients with a higher than median baseline T2H2O (>40.6 ms) in the right vastus medialis deteriorated 11 points more on the North Star Ambulatory Assessment for Dysferlinopathy and lost an additional 86 m on the 6‐min walk than those with a lower T2H2O (<40.6 ms). Optimum sensitivity and specificity thresholds for predicting decline were 39.0 ms in adductor magnus and vastus intermedius, 40.0 ms in vastus medialis, and 40.5 ms in vastus lateralis from different sites equipped with different MRI systems.
Conclusions
In dysferlinopathy, T2H2O did not correlate with current functional ability. However, T2H2O at baseline was higher in patients who worsened more rapidly on functional tests. This suggests that inter‐patient differences in functional decline over time may be, in part, explained by different severities of the active muscle damage, assessed by T2H2O measure at baseline. Significant challenges remain in standardizing T2H2O values across sites to allow determining globally applicable thresholds. The results from the present work are encouraging and suggest that T2H2O could be used to improve prognostication, patient selection, and disease modelling for clinical trials.
Practice of sports during childhood or adolescence correlates with an earlier onset and more rapidly progressing phenotype in dysferlinopathies. To determine if this correlation relates to greater ...muscle pathology that persists into adulthood, we investigated the effect of exercise on the degree of muscle fatty replacement measured using muscle MRI. We reviewed pelvic, thigh and leg T1W MRI scans from 160 patients with genetically confirmed dysferlinopathy from the Jain Foundation International clinical outcomes study in dysferlinopathy. Two independent assessors used the Lamminen-Mercuri visual scale to score degree of fat replacement in each muscle. Exercise intensity for each individual was defined as no activity, minimal, moderate, or intensive activity by using metabolic equivalents and patient reported frequency of sports undertaken between the ages of 10 and 18. We used ANCOVA and linear modeling to compare the mean Lamminen-Mercuri score for the pelvis, thigh, and leg between exercise groups, controlling for age at assessment and symptom duration. Intensive exercisers showed greater fatty replacement in the muscles of the pelvis than moderate exercisers, but no significant differences of the thigh or leg. Within the pelvis, Psoas was the muscle most strongly associated with this exercise effect. In patients with a short symptom duration of <15 years there was a trend toward greater fatty replacement in the muscles of the thigh. These findings define key muscles involved in the exercise-phenotype effect that has previously been observed only clinically in dysferlinopathy and support recommendations that pre-symptomatic patients should avoid very intensive exercise.
•Miscarriage and interventional delivery more common in neuromuscular disease.•Non-ambulant report more miscarriage and intervention than ambulant patients.•Gestational hypertension common in LGMD2A ...and myotonic dystrophy.•Falls during pregnancy common and risk should be addressed.•Specialist peri‑natal input should be considered for all.
Pregnancy and birth in women with neuromuscular conditions has been associated with more rapid disease progression and obstetric complications. This study assessed the impact of functional status and specific diagnosis on patient reported pregnancy and birth outcomes in 26 genetic neuromuscular diseases. Pregnancy and birth outcomes were collected through electronic patient questionnaires and analysed by mobility group and diagnosis. Free text responses were grouped into themes. 721 pregnancies were reported by 305 women. Miscarriage (21% of pregnancies), caesarean delivery (38% of births) and instrumental vaginal delivery (19% of births) were all more frequent in respondents than in the general population (p<0.05), and were more common in those who were non-ambulant at conception than other mobility levels (p <0.05). Falls occurred during 42% of pregnancies and a deterioration in muscle strength during 43%. There was not an increased incidence of maternal complications, apart from maternal hypertension which was more common in limb girdle muscular dystrophy 2A/R1 (35%) and myotonic dystrophy (24%). Patients offered specific practical advice to prospective mothers. Women with neuromuscular conditions have a more complex antenatal and perinatal course than unaffected women. Prenatal counselling, specialist obstetric review and additional occupational therapy support should be considered.
Objective
Dysferlinopathy is a muscular dystrophy with a highly variable clinical presentation and currently unpredictable progression. This variability and unpredictability presents difficulties for ...prognostication and clinical trial design. The Jain Clinical Outcomes Study of Dysferlinopathy aims to establish the validity of the North Star Assessment for Limb Girdle Type Muscular Dystrophies (NSAD) scale and identify factors that influence the rate of disease progression using NSAD.
Methods
We collected a longitudinal series of functional assessments from 187 patients with dysferlinopathy over 3 years. Rasch analysis was used to develop the NSAD, a motor performance scale suitable for ambulant and nonambulant patients. Generalized estimating equations were used to evaluate the impact of patient factors on outcome trajectories.
Results
The NSAD detected significant change in clinical progression over 1 year. The steepest functional decline occurred during the first 10 years after symptom onset, with more rapid decline noted in patients who developed symptoms at a younger age (p = 0.04). The most rapidly deteriorating group over the study was patients 3 to 8 years post symptom onset at baseline.
Interpretation
The NSAD is the first validated limb girdle specific scale of motor performance, suitable for use in clinical practice and clinical trials. Longitudinal analysis showed it may be possible to identify patient factors associated with greater functional decline both across the disease course and in the short‐term for clinical trial preparation. Through further work and validation in this cohort, we anticipate that a disease model incorporating functional performance will allow for more accurate prognosis for patients with dysferlinopathy. ANN NEUROL 2021;89:967–978
Aims
Dysferlinopathy is an autosomal recessive muscular dystrophy, caused by bi‐allelic variants in the gene encoding dysferlin (DYSF). Onset typically occurs in the second to third decade and is ...characterised by slowly progressive skeletal muscle weakness and atrophy of the proximal and/or distal muscles of the four limbs. There are rare cases of symptomatic DYSF variant carriers. Here, we report a large family with a dominantly inherited hyperCKaemia and late‐onset muscular dystrophy.
Methods and Results
Genetic analysis identified a co‐segregating novel DYSF variant NM_003494.4:c.6207del p.(Tyr2070Metfs*4). No secondary variants in DYSF or other dystrophy‐related genes were identified on whole genome sequencing and analysis of the proband's DNA. Skeletal muscle involvement was milder and later onset than typical dysferlinopathy presentations; these clinical signs manifested in four individuals, all between the fourth and sixth decades of life. All individuals heterozygous for the c.6207del variant had hyperCKaemia. Histological analysis of skeletal muscle biopsies across three generations showed clear dystrophic signs, including inflammatory infiltrates, regenerating myofibres, increased variability in myofibre size and internal nuclei. Muscle magnetic resonance imaging revealed fatty replacement of muscle in two individuals. Western blot and immunohistochemical analysis of muscle biopsy demonstrated consistent reduction of dysferlin staining. Allele‐specific quantitative PCR analysis of DYSF mRNA from patient muscle found that the variant, localised to the extreme C‐terminus of dysferlin, does not activate post‐transcriptional mRNA decay.
Conclusions
We propose that this inheritance pattern may be underappreciated and that other late‐onset muscular dystrophy cases with mono‐allelic DYSF variants, particularly C‐terminal premature truncation variants, may represent dominant forms of disease.
Dysferlinopathy is a rare, autosomal recessive muscular dystrophy, caused by bi‐allelic loss‐of‐function variants in DYSF. Here we describe a large family with a dominantly inherited hyperCKaemia and late‐onset progressive muscular dystrophy co‐segregating with a novel heterozygous DYSF frameshift variant. We propose that dominant dysferlinopathy may be underappreciated and should be considered for patients with a mono‐allelic variant if a secondary DYSF variant cannot be resolved after thorough genetic testing and analysis, particularly for those with C‐terminal premature protein truncation variants.
Background and objective
TK2 deficiency (TK2d) is a rare mitochondrial disorder that manifests predominantly as a progressive myopathy with a broad spectrum of severity and age of onset. The rate of ...progression is variable, and the prognosis is poor due to early and severe respiratory involvement. Early and accurate diagnosis is particularly important since a specific treatment is under development. This study aims to evaluate the diagnostic value of lower limb muscle MRI in adult patients with TK2d.
Methods
We studied a cohort of 45 genetically confirmed patients with mitochondrial myopathy (16 with mutations in
TK2
, 9 with mutations in other nuclear genes involved in mitochondrial DNA mtDNA synthesis or maintenance, 10 with single mtDNA deletions, and 10 with point mtDNA mutations) to analyze the imaging pattern of fat replacement in lower limb muscles. We compared the identified pattern in patients with TK2d with the MRI pattern of other non-mitochondrial genetic myopathies that share similar clinical characteristics.
Results
We found a consistent lower limb muscle MRI pattern in patients with TK2d characterized by involvement of the
gluteus maximus
,
gastrocnemius medialis
, and
sartorius
muscles. The identified pattern in TK2 patients differs from the known radiological involvement of other resembling muscle dystrophies that share clinical features.
Conclusions
By analyzing the largest cohort of muscle MRI from patients with mitochondrial myopathies studied to date, we identified a characteristic and specific radiological pattern of muscle involvement in patients with TK2d that could be useful to speed up its diagnosis.
•Initial diagnosis does not predict subsequent pattern of muscle weakness in dysferlinopathy.•Pattern of weakness is an overlapping continuum that does not form two distinct subgroups.•MM is a more ...common diagnosis in Japan than in Europe or the USA, but patients are not weaker distally.•Patients should not be split into MM and LGMDR2 subgroups for clinical trials.
This study aims to determine clinically relevant phenotypic differences between the two most common phenotypic classifications in dysferlinopathy, limb girdle muscular dystrophy R2 (LGMDR2) and Miyoshi myopathy (MMD1). LGMDR2 and MMD1 are reported to involve different muscles, with LGMDR2 showing predominant limb girdle weakness and MMD1 showing predominant distal lower limb weakness. We used heatmaps, regression analysis and principle component analysis of functional and Magnetic Resonance Imaging data to perform a cross-sectional review of the pattern of muscle involvement in 168 patients from the Jain Foundation's international Clinical Outcomes Study for Dysferlinopathy. We demonstrated that there is no clinically relevant difference in proximal vs distal involvement between diagnosis. There is a continuum of distal involvement at any given degree of proximal involvement and patients do not fall into discrete distally or proximally affected groups. There appeared to be geographical preference for a particular diagnosis, with MMD1 being more common in Japan and LGMDR2 in Europe and the USA. We conclude that the dysferlinopathies do not form two distinct phenotypic groups and therefore should not be split into separate cohorts of LGMDR2 and MM for the purposes of clinical management, enrolment in clinical trials or access to subsequent treatments.
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