Early-Onset Autosomal Dominant Myopathy with Vacuolated Fibers and Tubular Aggregates but No Periodic Paralysis, in a Patient with the c.1583G>A (p.R528H) mutation in the CACNA1S Gene.

Dominant mutations in CACNA1S gene mainly causes hypokalemic periodic paralysis (PP)(hypoPP). A 68-year-old male proband developed a progressive proximal weakness from the age of 35. Muscle biopsy showed atrophic fibers with vacuoles containing tubular aggregates. Exome sequencing revealed a heterozygous p.R528H (c.1583G>A) mutation in the CACNA1S gene. CACNA1S-related HypoPP evolving to persistent myopathy in late adulthood is a well-known clinical condition. However, isolated progressive myopathy (without PP) was only exceptionally reported and never with an early onset. Reporting a case of early onset CACNA1S-related myopathy in a patient with no HypoPP we intend to alert clinicians to consider it in the differential diagnosis of younger adult-onset myopathies especially when featuring vacuolar changes.

A novel PHKA1 mutation associating myopathy and cognitive impairment: Expanding the spectrum of phosphorylase kinase b (PhK) deficiency.

Muscle phosphorylase kinase b deficiency (PhK) is a rare disorder of glycogen metabolism characterized by exercise-induced myalgia and cramps, myoglobinuria and progressive muscle weakness. PhK deficiency is due to mutations in the PHKA1 gene inherited in an X-linked manner and is associated to glycogenosis type VIII (GSD VIII also called GSD IXd). PHKA1 gene codes for the αM subunit of the PhK, a multimeric protein complex responsible for the control of glycogen breakdown in muscle. Until now, few patients have been reported with X-linked recessive muscle PhK deficiency due to PHKA1 mutations. All reported patients presented with exercise intolerance and mild myopathy and one of them had cognitive impairment, leading to speculate about a central nervous system involvement in GSD VIII. Here we report in a sibling a novel mutation in the PHKA1 gene associated with a progressive myopathy, exercise intolerance, muscle hypertrophy and cognitive impairment as an associated feature. This report expands the genetic and clinical spectrum of the extremely rare PHKA1-related PhK deficiency and presents new evidences about its involvement in brain development.

Novel Phenotypes and Cardiac Involvement Associated With DNA2 Genetic Variants.

Objectives: To report two novel DNA2 gene mutations causing early onset myopathy with cardiac involvement and late onset mitochondriopathy with rhabdomyolysis. Methods: We performed detailed clinical, muscle histopathology and molecular studies including mitochondrial gene NGS analysis in two patients (Patient 1 and 2), a mother and her son, belonging to a Mexican family, and a third sporadic French patient. Results: Patient 1 and 2 presented with an early onset myopathy associated with ptosis, velopharyngeal weakness, and cardiac involvement. Patient 3 presented rhabdomyolysis unmasking a mitochondrial disease characterized by a sensorineural hearing loss, ptosis, and lipomas. Muscle biopsies performed in all patients showed variable mitochondrial alterations. Patient 3 had multiple mtDNA deletion in his muscle. Genetic studies revealed a novel heterozygous frameshift mutation in DNA2 gene (c.2346delT p.Phe782Leufs*3) in P1 and P2, and a novel heterozygous missense mutation in DNA2 gene (c.578T>C p.Leu193Ser) in the P3. Conclusions: To date only few AD cases presenting either missense or truncating DNA2 variants have been reported. None of them presented with a cardiac involvement or rhabdomyolysis. Here we enlarge the genetic and phenotypic spectrum of DNA2-related mitochondrial disorders.

Choreoathetotic syndrome following cardiac surgery.

Movement disorders following heart surgery are very unusual. Post-pump chorea is mainly a pediatric complication of heart surgery, typically manifesting after a latent period of normality and is usually related with long extracorporeal circulation time and deep hypothermia. We report a 73-year-old woman, without risk factors predisposing to paroxysmal movement disorders, presenting acute choreoathetoid movements 5 days after aortic valvular replacement with normal extracorporeal circulation time and perioperative normothermia.

New treatments for myasthenia: a focus on antisense oligonucleotides.

Autoimmune myasthenia gravis (MG) is a neuromuscular disorder caused by autoantibodies directed against the acetylcholine receptor (AChR). Current symptomatic therapy is based on acetylcholinesterase (AChE) drugs. The available long-term current therapy includes steroids and other immunomodulatory agents. MG is associated with the production of a soluble, rare isoform of AChE, also referred as the "read-through" transcript (AChE-R). Monarsen (EN101) is a synthetic antisense compound directed against the AChE gene. Monarsen was administered in 16 patients with MG and 14 patients achieved a clinically significant response. The drug is now in a Phase II study. Further investigations are required to confirm its long-term effects.