Bethlem myopathy: long-term follow-up identifies COL6 mutations predicting severe clinical evolution.

OBJECTIVE: Mutations in one of the 3 genes encoding collagen VI (COLVI) are responsible for a group of heterogeneous phenotypes of which Bethlem myopathy (BM) represents the milder end of the spectrum. Genotype-phenotype correlations and long-term follow-up description in BM remain scarce. METHODS: We retrospectively evaluated the long-term clinical evolution, and genotype-phenotype correlations in 35 genetically identified BM patients (23 index cases). RESULTS: Nineteen patients showed a typical clinical picture with contractures, proximal weakness and slow disease progression while 11 presented a more severe evolution. Five patients showed an atypical presentation, namely a limb girdle muscle weakness in 2 and a congenital myopathy pattern with either no contractures, or only limited to ankles, in 3 of them. Pathogenic COL6A1-3 mutations were mostly missense or in frame exon-skipping resulting in substitutions or deletions. Twenty one different mutations were identified including 12 novel ones. The mode of inheritance was, autosomal dominant in 83% of the index patients (including 17% (N=4) with a de novo mutation), recessive in 13%, and undetermined in one patient. Skipping of exon 14 of COL6A1 was found in 35% of index cases and was mostly associated with a severe clinical evolution. Missense mutations were detected in 39% of index cases and associated with milder forms of the disease. CONCLUSIONS: Long-term follow-up identified important phenotypic variability in this cohort of 35 BM patients. However, worsening of the functional disability appeared typically after the age of 40 in 47% of our patients, and was frequently associated with COL6A1 exon 14 skipping.

Polymicrogyria with dysmorphic basal ganglia? Think tubulin!

Dominant mutations in TUBB2B have been reported in patients with polymicrogyria. We further explore the phenotype associated with mutations in TUBB2B. Twenty patients with polymicrogyria (five unilateral) were tested for mutations in TUBB2B by Sanger sequencing. We identified two novel de novo mutations, c.743C>T (p.Ala248Val) and c.1139G>T (p.Arg380Leu) in exon 4 of TUBB2B in three unrelated families. Brain magnetic resonance images showed polymicrogyria involving predominantly the perisylvian regions. In addition, there was a dysmorphic appearance of the basal ganglia, thin corpus callosum, enlargement of the ventricles, thinning of the white matter and hypoplasia of pons and cerebellar vermis. This combination of associated features was absent in all 17 patients with polymicrogyria in whom no mutation was identified. This report underlines that the association of polymicrogyria with thin or absent corpus callosum, dysmorphic basal ganglia, brainstem and vermis hypoplasia is highly likely to result from mutations in TUBB2B and provides further insight in how mutations in TUBB2B affect protein function.

Safety, tolerability and pharmacokinetics of eteplirsen in young boys aged 6-48 months with Duchenne muscular dystrophy amenable to exon 51 skipping.

Eteplirsen is FDA-approved for the treatment of Duchenne muscular dystrophy (DMD) in exon 51 skip-amenable patients. Previous studies in boys > 4 years of age indicate eteplirsen is well tolerated and attenuates pulmonary and ambulatory decline compared with matched natural history cohorts. Here the safety, tolerability and pharmacokinetics of eteplirsen in boys aged 6-48 months is evaluated. In this open-label, multicenter, dose-escalation study (NCT03218995), boys with a confirmed mutation of the DMD gene amenable to exon 51 skipping (Cohort 1: aged 24-48 months, n = 9; Cohort 2: aged 6 to < 24 months, n = 6) received ascending doses (2, 4, 10, 20, 30 mg/kg) of once-weekly eteplirsen intravenously over 10 weeks, continuing at 30 mg/kg up to 96 weeks. Endpoints included safety (primary) and pharmacokinetics (secondary). All 15 participants completed the study. Eteplirsen was well tolerated with no treatment-related discontinuations, deaths or evidence of kidney toxicity. Most treatment-emergent adverse events were mild; most common were pyrexia, cough, nasopharyngitis, vomiting, and diarrhea. Eteplirsen pharmacokinetics were consistent between both cohorts and with previous clinical experience in boys with DMD > 4 years of age. These data support the safety and tolerability of eteplirsen at the approved 30-mg/kg dose in boys as young as 6 months old.

Expression of full-length utrophin prevents muscular dystrophy in mdx mice.

Duchenne muscular dystrophy (DMD) is a lethal, progressive muscle wasting disease caused by a loss of sarcolemmal bound dystrophin, which results in the death of the muscle fiber leading to the gradual depletion of skeletal muscle. The molecular structure of dystrophin is very similar to that of the related protein utrophin. Utrophin is found in all tissues and is confined to the neuromuscular and myotendinous junctions in mature muscle. Sarcolemmal localization of a truncated utrophin transgene in the dystrophin-deficient mdx mouse significantly improves the dystrophic muscle phenotype. Therefore, up-regulation of utrophin by drug therapy is a plausible therapeutic approach in the treatment of DMD. Here we demonstrate that expression of full-length utrophin in mdx mice prevents the development of muscular dystrophy. We assessed muscle morphology, fiber regeneration and mechanical properties (force development and resistance to stretch) of mdx and transgenic mdx skeletal and diaphragm muscle. The utrophin levels required in muscle are significantly less than the normal endogenous utrophin levels seen in lung and kidney, and we provide evidence that the pathology depends on the amount of utrophin expression. These results also have important implications for DMD therapies in which utrophin replacement is achieved by delivery using exogenous vectors.

Expression of truncated utrophin leads to major functional improvements in dystrophin-deficient muscles of mice.

Dystrophin-deficient mice (mdx) expressing a truncated (trc) utrophin transgene show amelioration of the dystrophic phenotype. Here we report a multifunctional study demonstrating that trcutrophin expression leads to major improvements of the mechanical performance of muscle (that is, force development, mechanical resistance to forced lengthenings and maximal spontaneous activity) and of the maintenance of the intracellular calcium homeostasis. These are two essential functions of muscle fibers, known to be impaired in mdx mouse muscles and Duchenne muscular dystrophy (DMD) patients. Our results bring strong support to the hypothesis that muscle wasting in dystrophin-deficient DMD patients could be prevented by upregulation of utrophin.

Correlation between urine ketones (acetoacetate) and capillary blood ketones (3-beta-hydroxybutyrate) in hyperglycaemic patients.

AIMS: To facilitate the transition from urine ketones (acetoacetate) to capillary blood ketones (3-beta-hydroxybutyrate), we studied the correlation between these two tests. METHODS: Retrospective study of all patients with blood glucose greater than or equal to 2.5 g/l on arrival in the Emergency Department. We studied the correlation between urine ketones (Clinitek 50, Bayer) and capillary blood ketones (Optium, Abbott). We then compared the relative risks (RR) of ketoacidosis and hospitalization associated with each of these tests. RESULTS: In 33 months, 529 adult patients with both urine and blood testing for ketones were enrolled (ketoacidosis 8%, admission rate 49%). Urine ketones scored as +, ++ and +++ corresponded to median capillary blood ketone levels of 0.5 mmol/l (IQR: 0.1-0.9), 0.7 mmol/l (IQR: 0.2-1.8) and 3 mmol/l (IQR: 1.4-5.2), respectively. RRs of ketoacidosis or hospitalization associated with blood ketones greater than or equal to 3 mmol/l were higher than those associated with +++ urine ketones: 74 (95% confidence interval [CI]: 48-88) and 2.9 (95% CI: 2.5-3) versus 31 (95% CI: 18-45) and 2 (95% CI: 1.7-2.1), respectively. CONCLUSIONS: In hyperglycaemic patients in the Emergency Department, a good correlation was observed between urine ketones and capillary blood ketones for low values, but a poor correlation was observed for high values. Either test can therefore be used to exclude ketosis, but the capillary blood ketones test is more accurate to confirm ketoacidosis.

MALDI-MS profiling of serum O-glycosylation and N-glycosylation in COG5-CDG.

Congenital disorders of glycosylation (CDG) are due to defective glycosylation of glycoconjugates. Conserved oligomeric Golgi (COG)-CDG are genetic diseases due to defects of the COG complex subunits 1-8 causing N-glycan and O-glycan processing abnormalities. In COG-CDG, isoelectric focusing separation of undersialylated glycoforms of serum transferrin and apolipoprotein C-III (apoC-III) allows to detect N-glycosylation and O-glycosylation defects, respectively. COG5-CDG (COG5 subunit deficiency) is a multisystem disease with dysmorphic features, intellectual disability of variable degree, seizures, acquired microcephaly, sensory defects and autistic behavior. We applied matrix-assisted laser desorption/ionization-MS for a high-throughput screening of differential serum O-glycoform and N-glycoform in five patients with COG5-CDG. When compared with age-matched controls, COG5-CDG showed a significant increase of apoC-III0a (aglycosylated glycoform), whereas apoC-III1 (mono-sialylated glycoform) decreased significantly. Serum N-glycome of COG5-CDG patients was characterized by the relative abundance of undersialylated and undergalactosylated biantennary and triantennary glycans as well as slight increase of high-mannose structures and hybrid glycans. Using advanced and well-established MS-based approaches, the present findings reveal novel aspects on O-glycan and N-glycan profiling in COG5-CDG patients, thus providing an increase of current knowledge on glycosylation defects caused by impairment of COG subunits, in support of clinical diagnosis. Copyright © 2017 John Wiley & Sons, Ltd.

[A new framework for cerebral palsy]. / Un nouveau cadre conceptuel pour l'infirmité motrice cérébrale.

Cerebral palsy was recently redefined as a group of disorders of the development of movement and posture, causing activity limitation, that are attributed to non-progressive disturbances that occurred in the developing fetal or infant brain. The motor disorders of cerebral palsy are often accompanied by disturbances of sensation, perception, cognition, communication or behaviour, by epilepsy or by secondary musculoskeletal problems (Bax et al. 2005). It has an estimated incidence of 0.2 %, i.e., 200 new cases per year in Belgium and a total of about 18,000 patients (in a population of 10 millions). Over the last few years, interest has risen in issues pertaining to learning, social participation, services, some assessment modalities (including gait analysis), some therapeutic modalities (including orthotics and antispastic treatment). The Department of Neurology of the H6pital Universitaire des Enfants Reine Fabiola has taken an active part in several aspects of these developments, including research on pathophysiology, neurophysiology, motor control and management (including intrathecal baclofen) as well as setting up the Interuniversity Reference Centre for Cerebral Palsy ULB-VUB-ULg. The 20th anniversary of the hospital offers an opportunity to review this important topic.

Critical illness myopathy unrelated to corticosteroids or neuromuscular blocking agents.

Acute myopathy occurs in critically ill patients, receiving neuromuscular blocking agents or corticosteroids during intensive care hospitalisation. We report three patients with acute quadriplegic myopathy, two of whom were not exposed to corticosteroids or neuromuscular blocking agents. The first of these latter two patients had a history of generalised anoxia with coma related to surgery, complicated by multiple organ failure and sepsis. The second patient, suffering from acute leukaemia, developed sepsis and acute respiratory distress syndrome with the need for mechanical ventilation in the intensive care unit. Electrophysiological studies and muscle biopsy findings were consistent with the diagnosis of critical illness myopathy with loss of myosin filaments. Selective loss of myosin was confirmed by biochemical analysis of muscle. These findings demonstrate that acute myopathy with loss of myosin filaments may occur in patients with severe systemic illness without exposure to corticosteroids or neuromuscular blocking agents.

Consequences of the combined deficiency in dystrophin and utrophin on the mechanical properties and myosin composition of some limb and respiratory muscles of the mouse.

The mechanical properties and the myosin isoform composition were studied in three isolated muscles (EDL, soleus, diaphragm) of mutant mice lacking both dystrophin and utrophin (dko). They were compared with the corresponding muscles of the normal and the dystrophin-deficient (mdx) and the utrophin-deficient (uko) mice. In comparison with mdx muscles, dko muscles show a significant reduction of the normalized isometric force, confirmed by the reduced muscular activity of the whole animal. Kinetics parameters (twitch time-to-peak and half-relaxation time) were slightly reduced, and the maximal speed of shortening of soleus, Vmax, was reduced by 30%. The maximal power output (muW/mm3) was reduced by 50% in dko soleus. In the three muscles studied, the relative myosin heavy chains (MHC) composition showed a shift towards slower isoforms. dko EDL presented a dramatic decrease of the resistance ot tetanic contraction with forced lengthenings (eccentric contractions), while muscle lacking only utrophin (uko mutants) display a normal resistance to this exacting mechanical challenge. These experiments suggest that lack of both dystrophin and utrophin is very detrimental to the mice and that mechanical properties of the muscles may explain the overall phenotype. Moreover these results bring some support to the idea that the expression of utrophin in mdx muscle compensates, to some extent, for the lack of dystrophin.

Expression of truncated utrophin improves pH recovery in exercising muscles of dystrophic mdx mice: a 31P NMR study.

31P NMR spectroscopy was used to study the energy metabolism of dystrophin-deficient skeletal muscle of mdx mice, an animal model of Duchenne muscular dystrophy, in which expression of a truncated form of utrophin has been obtained through transgenesis technology. Measurements of ATP, phosphocreatine (PCr), inorganic phosphates (Pi) and intracellular pH (pHi) were made at rest, during a fatigue protocol and during the subsequent recovery. Mechanical fatigue of transgenic muscles was similar to normal muscle, while mdx muscle showed larger force loss. At rest, muscles of all groups had similar values for [ATP], [PCr], [Pi] and pHi. During fatigue, [PCr] decreases mirrored [Pi] increases and were similar in all groups. The major difference between mdx muscles and the group of normal and trc-utrophin muscles concerned the values and evolution of pHi. The mdx muscles showed a more severe intracellular acidosis during exercise and a slower and incomplete post-exercise recovery of normal pHi. In contrast, in trc-utrophin muscles, the kinetics and amplitude of pHi changes were remarkably close to normal behaviour. We conclude that the impaired proton washout which is present in mdx muscles, is corrected to a great extent by the expression of trc-utrophin.

Effect of muscle denervation on the expression of substance P in the ventral raphe-spinal pathway of the rat.

The medullary raphe nuclei, wherein serotonin (5-HT) coexists with substance P (SP) and thyrotropin-releasing hormone (TRH), innervate lower motor neurons in the spinal cord ventral horn by means of the ventral raphe-spinal pathway. Destruction of the ventral raphe-spinal pathway is associated with deficient recovery of denervated muscle, indicating that it may exert a trophic effect upon lower motor neurons. To determine whether SP could be a trophic factor for lower motor neurons within the ventral raphe-spinal pathway, the effect of muscle denervation with botulinum toxin type A on SP-encoding beta-preprotachykinin mRNA in the rat medullary raphe was examined by in situ hybridization histochemistry. Silver grain density over hybridized medullary raphe neurons was increased by up to 11%, although the number of hybridized neurons did not change in denervated as compared to control rats. Increased SP gene expression in the medullary raphe in response to motor unit lesioning suggests that raphe-spinal SP may be trophic to lower motor neurons.

Adult-onset nemaline myopathy and monoclonal gammopathy: a case report.

A 47-year-old female developed proximal limb weakness after hysterectomy for uterine fibromatosis. Muscle strength slowly improved, but relapse occurred at age 52. She presented with progressive gait difficulty, proximal limb weakness, and painful calves. Family history was not contributory. Cranial nerves, deep tendon reflexes, and sensation were normal. Serum creatine kinase was normal. An IgG kappa monoclonal protein was found. Nerve conduction studies were normal, but EMG showed brief small polyphasic motor unit action potentials with early recruitment in proximal muscles. Muscle biopsy showed abundant rods, atrophic muscle fibres, and type 1 fibre predominance. The sarcolemma was immunoreactive for IgG kappa. Plasmapheresis was unsuccessful, but methylprednisolone and azathioprine led to moderate improvement of muscle strength, associated with reduced monoclonal protein levels. This is the third case report, describing the association of monoclonal gammopathy and late-onset nemaline myopathy. Presence of a monoclonal protein at the sarcolemma and responsiveness to immunosuppressive treatment are suggestive of a dys-immune origin.

Behavioral and neurophysiological study of attentional and inhibitory processes in ADHD-combined and control children.

This study compares behavioral and electrophysiological (P300) responses recorded in a cued continuous performance task (CPT-AX) performed by children with attention deficit hyperactivity disorder-combined subtype (ADHD-com) and age-matched healthy controls. P300 cognitive-evoked potentials and behavioral data were recorded in eight children with ADHD (without comorbidity) and nine control children aged 8-12 years while performing a CPT-AX task. Such task enables to examine several kinds of false alarms and three different kinds of P300 responses: the "Cue P300", the "Go P300" and the "NoGo P300", respectively, associated with preparatory processing/attentional orienting, motor/response execution and motor/response inhibition. Whereas hit rates were about 95% in each group, ADHD children made significantly more false alarm responses (inattention- and inhibition-related) than control children. ADHD children had a marginally smaller Cue P300 than the control children. Behavioral and electrophysiological findings both highlighted inhibition and attention deficits in ADHD-com children in the CPT-AX task. A rarely studied kind of false alarm, the "Other" FA, seems to be a sensitive FA to take into account, even if its interpretation remains unclear.

Innovative methods to assess upper limb strength and function in non-ambulant Duchenne patients.

Upper limb assessment in non-ambulant patients remains a challenge. We have designed new tools to precisely assess pinch (MyoPinch), grip (MyoGrip), wrist flexion and extension (MyoWrist) strength. We have also designed a new tool to assess the ability of patients to produce repetitive flexion/extension movements of wrist and fingers (MoviPlate). We have assessed the feasibility and reliability of these new tools in 30 non-ambulant patients with Duchenne muscular dystrophy and in 30 age-matched male controls. Existing measures, such as Motor Function Measure, Tapping, and the Brooke Upper Extremity Functional Rating Scale were also performed. Results demonstrated that assessments were feasible in nearly all upper limbs tested for MyoGrip, MyoPinch and MoviPlate. The reliability of all tests, including MyoWrist which was not feasible in the patients presenting with contractures, was excellent in patients as in controls. Motor capacities decrease with the number of months spent in the wheelchair. The scores in the tests were partially correlated with each other, and with clinical measures such as vital capacity, Motor Function Measure, functional hand scale and Brooke score. This study validates a panel of upper limb muscle strength and function measures for Duchenne Muscular Dystrophy which can be applied from controls to extremely weak patients.

The H reflex as a diagnostic tool for Miller Fisher syndrome in pediatric patients.

Miller Fisher syndrome (MFS) is characterized by gait ataxia, external ophthalmoplegia and areflexia. Immunohistochemical studies suggest a pathophysiological role for anti-GQ1b antibodies at the paranodal regions of the oculomotor nerves, at some neurons of the dorsal root ganglia (DRG) and at motor nerve terminals. The variability of abnormal electrophysiological findings reported is significant. Nerve conduction studies, H reflex and F waves were performed in three pediatric patients with MFS. The H reflex was absent in all three patients. It was the sole abnormality in two patients whereas the third patient also had extended motor and sensory nerve conduction impairments. The transient character of this isolated absence has been confirmed in one patient. These data point to a proximal demyelinating process near the DRG. This may involve selective demyelination of Ia spinocerebellar afferent fibers originating in muscle spindles. In a pediatric practice, the H reflex seems to be a useful tool in the diagnostic approach to MFS.

Differentiating Emery-Dreifuss muscular dystrophy and collagen VI-related myopathies using a specific CT scanner pattern.

Bethlem myopathy and Ullrich congenital muscular dystrophy are part of the heterogeneous group of collagen VI-related muscle disorders. They are caused by mutations in collagen VI (ColVI) genes (COL6A1, COL6A2, and COL6A3) while LMNA mutations cause autosomal dominant Emery-Dreifuss muscular dystrophy. A muscular dystrophy pattern and contractures are found in all three conditions, making differential diagnosis difficult especially in young patients when cardiomyopathy is absent. We retrospectively assessed upper and lower limb muscle CT scans in 14 Bethlem/Ullrich patients and 13 Emery-Dreifuss patients with identified mutations. CT was able to differentiate Emery-Dreifuss muscular dystrophy from ColVI-related myopathies in selected thigh muscles and to a lesser extent calves muscles: rectus femoris fatty infiltration was selectively present in Bethlem/Ullrich patients while posterior thigh muscles infiltration was more prominently found in Emery-Dreifuss patients. A more severe fatty infiltration particularly in the leg posterior compartment was found in the Emery-Dreifuss group.

Functional protection of dystrophic mouse (mdx) muscles after adenovirus-mediated transfer of a dystrophin minigene.

Fast skeletal muscles of mdx (X chromosome-linked muscular dystrophy) mice were injected after birth with a recombinant adenovirus containing a minidys- trophin gene, a 6.3-kbp cDNA coding for the N- and C-terminal ends of dystrophin. Adult muscles were challenged by forced lengthening during tetanic contractions. Stretch-induced mechanical and histological damages were much reduced in injected muscles, in direct proportion of the Miniber of fibers expressing minidystrophin. Damaged fibers were preferentially found among minidystrophin-negative regions. Minidystrostrophin confers an important functional and structural protection of limb muscles against high mechanical stress, even after a partial somatic gene transfer.

Familial bilateral medial parietooccipital band heterotopia not related to DCX or LIS1 gene defects.

A father and his daughter displayed strictly similar focal brain dysplasia at MR examination, characterized by regional medial posterior laminar sub-cortical grey matter heterotopia. To our knowledge, no family presenting such anomalies has yet been described. LIS1 and DCX gene defects were excluded. Collecting patients with such inherited dysplasia should improve our knowledge of the genetic basis of cortical malformations.