Combination molecular therapies for type 1 spinal muscular atrophy.

BACKGROUND: Data on combining molecular therapies that increase survival motor neuron protein for spinal muscular atrophy type 1 (SMA1) is lacking. METHODS: This was a retrospective study describing our centers' experiences in treating SMA1 patients with combination therapy. RESULTS: Five children received nusinersen and onasemnogene abeparvovec-xioi (onasemnogene). Four were receiving nusinersen prior to onasemnogene. Nusinersen was continued in three. Marked liver enzyme elevations resulted in prolonged corticosteroid treatment in two patients with hospitalization and liver biopsy in one; milder liver enzyme elevations were noted in the other two. One patient received onasemnogene first, and then nusinersen. No adverse effects were noted. All patients improved. CONCLUSIONS: Combination molecular therapy is tolerated in SMA1 patients. Further studies are needed to determine whether there are circumstances in which combination therapy would be more efficacious than either monotherapy. Prolonged corticosteroid use and liver toxicity monitoring may be necessary with onasemnogene therapy.

Constitutive activation of the PI3K-AKT pathway and cardiovascular abnormalities in an individual with Kosaki overgrowth syndrome.

Kosaki overgrowth syndrome is a recently described syndrome characterized by distinctive facial features, brain white matter lesions, and developmental delay. Germline activating heterozygous PDGFRB mutations have been reported in this condition. Systemic connective tissue-type findings have been described in some individuals. We describe a 19-year-old Caucasian female with a history of hydrocephalus, Dandy-Walker malformation, cervical spine arachnoid cyst, progressive scoliosis, and overgrowth. Her physical exam included distinctive craniofacial dysmorphism, as well as soft and hyperextensible skin. Cardiovascular imaging during adolescence revealed saccular aneurysms in both coronary artery systems and subtle tortuosity of the cervical vertebral arteries. Exome sequencing trio analysis identified a de novo previously reported pathogenic variant in PDGFRB, c.1696T>C (p.[Trp566Arg]). Further functional studies included platelet-derived growth factor cellular metabolic pathway activity that confirmed the variant causes a constitutive activation of the PI3K-AKT pathway. This is the first report to characterize the activating nature of this PDGFRB variant. We also highlight the connective tissue findings seen in Kosaki overgrowth syndrome and recommend baseline echocardiographic evaluation in all individuals with this condition with particular emphasis on coronary arteries.

Clinical and molecular spectrum of thymidine kinase 2-related mtDNA maintenance defect.

Mitochondrial DNA maintenance (mtDNA) defects have a wide range of causes, each with a set of phenotypes that overlap with many other neurological or muscular diseases. Clinicians face the challenge of narrowing down a long list of differential diagnosis when encountered with non-specific neuromuscular symptoms. Biallelic pathogenic variants in the Thymidine Kinase 2 (TK2) gene cause a myopathic form of mitochondrial DNA maintenance defect. Since the first description in 2001, there have been 71 patients reported with 42 unique pathogenic variants. Here we are reporting 11 new cases with 5 novel pathogenic variants. We describe and analyze a total of 82 cases with 47 unique TK2 pathogenic variants in effort to formulate a comprehensive molecular and clinical spectrum of TK2-related mtDNA maintenance disorders.

GMPPB-Associated Dystroglycanopathy: Emerging Common Variants with Phenotype Correlation.

Mutations in GDP-mannose pyrophosphorylase B (GMPPB), a catalyst for the formation of the sugar donor GDP-mannose, were recently identified as a cause of muscular dystrophy resulting from abnormal glycosylation of α-dystroglycan. In this series, we report nine unrelated individuals with GMPPB-associated dystroglycanopathy. The most mildly affected subject has normal strength at 25 years, whereas three severely affected children presented in infancy with intellectual disability and epilepsy. Muscle biopsies of all subjects are dystrophic with abnormal immunostaining for glycosylated α-dystroglycan. This cohort, together with previously published cases, allows preliminary genotype-phenotype correlations to be made for the emerging GMPPB common variants c.79G>C (p.D27H) and c.860G>A (p.R287Q). We observe that c.79G>C (p.D27H) is associated with a mild limb-girdle muscular dystrophy phenotype, whereas c.860G>A (p.R287Q) is associated with a relatively severe congenital muscular dystrophy typically involving brain development. Sixty-six percent of GMPPB families to date have one of these common variants.

Limb-Girdle Muscular Dystrophy R9 due to a Novel Complex Insertion/Duplication Variant in FKRP Gene.

Limb-girdle muscular dystrophy R9 (LGMD2I, LGMDR9) is an autosomal recessive disorder caused by pathogenic variants in the fukutin-related protein (FKRP) gene. We describe a 17 year old boy with LGMDR9 whose symptoms began at age 5 years. Muscle histopathology, immunostaining, and western blotting were consistent with a dystroglycanopathy. Genetic testing identified maternal inheritance of the most common pathogenic FKRP variant c.826C>A (p.L276I). Also detected was a novel insertion and duplication on the paternally inherited FKRP allele: a single nucleotide insertion (c.948_949insC) and an eighteen nucleotide duplication (c.999_1017dup18) predicted to result in premature translation termination (p.E389*). Based on the clinical features and course of the patient, heterozygosity for the common pathogenic FKRP variant, and abnormal glycosylation of alpha-dystroglycan, we suggest that the novel FKRP insertion and duplication are pathogenic. This case expands the genetic heterogeneity of LGMDR9 and emphasize the importance of muscle biopsy for precise diagnosis.

BAG3 Myopathy Presenting With Prominent Neuropathic Phenotype and No Cardiac or Respiratory Involvement: A Case Report and Literature Review.

Bcl-2-associated athanogene 3 (BAG3) myopathy is a rare myofibrillar myopathy characterized by toe walking and clumsiness in the first decade with rapid progression to cardiomyopathy and restrictive lung disease in the second decade. Most patients (18 patients) have the c.626C >T (p.Pro209Leu) mutation. We describe BAG3 myopathy due to p.Pro209Leu in a 13-year-old girl with initial prominent neuropathic phenotype and no cardiac or respiratory involvement. Parents reported toe walking and clumsiness since 3 years old. Examination at the age of 13 years showed findings suggestive of Charcot-Marie-Tooth disease. Nerve conduction studies revealed demyelinating polyneuropathy. Next-generation sequencing panel for inherited neuropathies was unrevealing. Whole exome sequencing identified a de novo mutation in BAG3. Muscle biopsy confirmed myofibrillar myopathy. No cardiac involvement or symptoms of respiratory involvement at the age of 14 years. This case emphasizes the phenotypic variability of BAG3 myopathy and the importance of thorough electrophysiological examination and muscle pathology for establishing a precise diagnosis.

Toxic Myopathy due to Antidopaminergic Medication Without Neuroleptic Malignant Syndrome.

Severe recurrent proximal muscle weakness without neuroleptic malignant syndrome secondary to antidopaminergic medication has rarely been reported. We report a 29-year-old man with history of obsessive compulsive disorder and Tourette syndrome who presented with 2 months of worsening dyspnea 3 weeks after starting ziprasidone 40 mg daily that required mechanical ventilation. A year before, after an increased risperidone dose from 0.5 to 1 mg daily, he had developed proximal muscle weakness that spontaneously improved 2 months after discontinuation of risperidone. On this admission, his creatine kinase (CK) was 3318 units/L, and ziprasidone was discontinued. He fully recovered 2 months after discontinuation of ziprasidone, and his CK was 62 units/L. Genetic testing for limb-girdle muscular dystrophy was negative. This case highlights the importance of evaluating CK level in patients taking antidopaminergic medication with any suggestion of muscle weakness to prevent potentially life-threatening complication.

De novo variants in EBF3 are associated with hypotonia, developmental delay, intellectual disability, and autism.

Using whole-exome sequencing, we identified seven unrelated individuals with global developmental delay, hypotonia, dysmorphic facial features, and an increased frequency of short stature, ataxia, and autism with de novo heterozygous frameshift, nonsense, splice, and missense variants in the Early B-cell Transcription Factor Family Member 3 (EBF3) gene. EBF3 is a member of the collier/olfactory-1/early B-cell factor (COE) family of proteins, which are required for central nervous system (CNS) development. COE proteins are highly evolutionarily conserved and regulate neuronal specification, migration, axon guidance, and dendritogenesis during development and are essential for maintaining neuronal identity in adult neurons. Haploinsufficiency of EBF3 may affect brain development and function, resulting in developmental delay, intellectual disability, and behavioral differences observed in individuals with a deleterious variant in EBF3.

Experiences from the development of a comprehensive family support program for pediatric trauma and rehabilitation patients.

This report discusses the successes and problems associated with the development of a family support system designed to improve outcomes in a pediatric trauma population. Studies have demonstrated lowered health-related quality of life among injured children during rehabilitation, along with substantial parental stress. By developing comprehensive support services for families, we may decrease parental burden and improve parents ability to care for their children, thus improving health outcomes for them. Through analysis of data from a longitudinal study of injured children, focus group interviews with affected families, and consultation with a multidisciplinary team, interventions were developed. The resulting program consists of 3 main components: (1) efforts to increase coordination of discharge care, (2) establishment of educational protocols, and (3) implementation of support groups and a peer support program for families. Patient satisfaction and reported use of program materials is high; efforts to improve education, regarding transitions to school and other activities, are continuing. Early evaluation of the program suggests that it is effectively addressing family needs; evaluation of the programs long-term effect is ongoing. We are able to discuss successes and barriers to program implementation and make recommendations for others considering such an undertaking.