Sergiu C. Blumen

Immortalized pathological human myoblasts: towards a universal tool for the study of neuromuscular disorders

BackgroundInvestigations into both the pathophysiology and therapeutic targets in muscle dystrophies have been hampered by the limited proliferative capacity of human myoblasts. Isolation of reliable and stable immortalized cell lines from patient biopsies is a powerful tool for investigating pathological mechanisms, including those associated with muscle aging, and for developing innovative gene-based, cell-based or pharmacological biotherapies.MethodsUsing transduction with both telomerase-expressing and cyclin-dependent kinase 4-expressing vectors, we were able to generate a battery of immortalized human muscle stem-cell lines from patients with various neuromuscular disorders.ResultsThe immortalized human cell lines from patients with Duchenne muscular dystrophy, facioscapulohumeral muscular dystrophy, oculopharyngeal muscular dystrophy, congenital muscular dystrophy, and limb-girdle muscular dystrophy type 2B had greatly increased proliferative capacity, and maintained their potential to differentiate both in vitro and in vivo after transplantation into regenerating muscle of immunodeficient mice.ConclusionsDystrophic cellular models are required as a supplement to animal models to assess cellular mechanisms, such as signaling defects, or to perform high-throughput screening for therapeutic molecules. These investigations have been conducted for many years on cells derived from animals, and would greatly benefit from having human cell models with prolonged proliferative capacity. Furthermore, the possibility to assess in vivo the regenerative capacity of these cells extends their potential use. The innovative cellular tools derived from several different neuromuscular diseases as described in this report will allow investigation of the pathophysiology of these disorders and assessment of new therapeutic strategies.

Homozygotes for oculopharyngeal muscular dystrophy have a severe form of the disease

Autosomal dominant oculopharyngeal muscular dystrophy (OPMD) usually begins with ptosis or dysphagia during the fifth or sixth decade of life. We studied 7 patients with OPMD symptoms starting before the age of 36 years. All were found to be homozygotes for the dominant (GCG)9 OPMD mutation. On average, disease onset was 18 years earlier than in heterozygotes, and patients had a significantly larger number of muscle nuclei containing intranuclear inclusions (INIs) (9.4 vs 4.9%). Ann Neurol 1999;46:115–118

Autosomal-recessive juvenile parkinsonism in a Jewish Yemenite kindred: Mutation of Parkin gene

We report a Jewish family of Yemenite origin in which three brothers born from a consanguineous marriage had juvenile parkinsonism. The DNA samples from three affected brothers and one healthy brother were analyzed for the linkage to markers covering the autosomal-recessive juvenile parkinsonism (AR-JP) locus. A perfect homozygous cosegregation to the markers was found, giving a maximal lod score of 3.11 at D6S1579, D6S305, and D6S411, all of which are 0 cm apart from each other (nonparametric linkage score, 8.041; p = 0.000977). Exon 3 of the Parkin gene was homozygously deleted in all patients. The AR-JP gene also exists in the Jewish population.

A locus for complicated hereditary spastic paraplegia maps to chromosome 1q24-q32.

We updated the clinical features of a consanguineous Arab Israeli family, in which four of seven children were affected by spastic paraplegia complicated by skin pigmentary abnormalities. A genomewide linkage screen performed for the family identified a new locus (SPG23) for this form of hereditary spastic paraplegia, in an approximately 25cM region of chromosome 1q24‐q32, with a peak logarithm of odds score of 3.05. Ann Neurol 2003;54:796–803

A rare recessive distal hereditary motor neuropathy with HSJ1 chaperone mutation.

Distal hereditary motor neuropathies (dHMN) form a clinically and genetically heterogeneous group of disorders, characterized by muscle weakness and atrophy predominating at the distal part of the limbs, due to the progressive degeneration of motor neurons in the spinal cord. We report here a novel rare variant of dHMN with autosomal recessive inheritance in a large Jewish family originating from Morocco. The disease is characterized by a predominance of paralysis at the lower limbs and an early adulthood onset. We performed a genetic study in this family to identify and characterized the causing mutation.

Camptocormia, axial dystonia, and parkinsonism: phenotypic heterogeneity of a parkin mutation.

Autosomal recessive juvenile parkinsonism (AR-JP) is a young-onset parkinsonism caused by mutations in the parkin gene.1 Exonic deletions or multiplications and truncating and missense mutations have been described.2,3⇓ The phenotype encompasses juvenile-, early-, and late-onset patients.2 We describe a large kindred with different phenotypic expressions of a mutation in the parkin gene. The patients belonged to two branches of an Arabic Israeli family (figure). Patients in Branch A have been previously described.4 The consanguinity of the branches was established to the seventh ancestral generation. Figure. The pedigree. Square symbols = men, circles = women, diagonal lines = deceased persons, ✓ = genotyped. The consanguinity of the branches of the family was established to the seventh ancestral generation. Four brothers (black squares) in Branch A (right) and two first-degree cousins (black square and circle) in Branch B (middle) are affected. All patients showed homozygous one adenine deletion at nucleotide position 202. The horizontal shaded symbols represent patients with tremor only who were clinically examined. The patient with an asterisk was genotyped …

Clinical features of oculopharyngeal muscular dystrophy among Bukhara Jews

Oculopharyngeal muscular dystrophy (OPMD), a late onset autosomal dominant myopathy, is common among the French-Canadians and the Jews from Bukhara (Uzbekistan); most clinical histologic and genetic data published until now, as well as the recently suggested diagnostic criteria, are based on studies among the former. We studied 79 patients with OPMD belonging to the newly described Jewish-Bukhara cluster. The disease began between the ages of 21 and 78 yr (median 53 yr). In 11 patients (15%) it began before the age of 40. Ptosis was the first symptom in 59 patients and dysphagia in the remaining 20. Eight patients (10%) were monosymptomatic (ptosis) after more than 7 yr from the start of the disease; however, other family members had additional signs/symptoms. The patients belong to 29 families; in 26 age-dependent autosomal dominant inheritance could be documented. Among them there is certain evidence for genetic anticipation. This clinical study is the largest published concerning patients other than French-Canadians.

Novel mutation in VCP gene causes atypical amyotrophic lateral sclerosis

Objective: To identify the genetic variant that causes autosomal dominantly inherited motor neuron disease in a 4-generation Israeli-Arab family using genetic linkage and whole exome sequencing. Methods: Genetic linkage analysis was performed in this family using Illumina single nucleotide polymorphism chips. Whole exome sequencing was then undertaken on DNA samples from 2 affected family members using an Illumina 2000 HiSeq platform in pursuit of potentially pathogenic genetic variants that comigrate with the disease in this pedigree. Variants meeting these criteria were then screened in all affected individuals. Results: A novel mutation (p.R191G) in the valosin-containing protein (VCP) gene was identified in the index family. Direct sequencing of the VCP gene in a panel of DNA from 274 unrelated individuals with familial amyotrophic lateral sclerosis (FALS) revealed 5 additional mutations. Among them, 2 were previously identified in pedigrees with a constellation of inclusion body myopathy with Paget disease of the bone and frontotemporal dementia (IBMPFD) and in FALS, and 2 other mutations (p.R159C and p.R155C) in IBMPFD alone. We did not detect VCP gene mutations in DNA from 178 cases of sporadic amyotrophic lateral sclerosis. Conclusions: We report a novel VCP mutation identified in an amyotrophic lateral sclerosis family (p.R191G) with atypical clinical features. In our experience, VCP mutations arise in approximately 1.5% of FALS cases. Our study supports the view that motor neuron disease is part of the clinical spectrum of VCP-associated disease.

Parkin gene causing benign autosomal recessive juvenile parkinsonism

Autosomal recessive juvenile parkinsonism (AR-JP) is an early-onset parkinsonism caused by exonic deletions or point mutations in the parkingene. The relationship between the type of the genetic defect and the clinical presentation, the response to therapy, and the evolution have not been yet determined. The authors describe a single-basepair deletion at nucleotide 202 in exon 2 of the parkin gene in a kindred with a benign clinical course.

Cognitive impairment and reduced life span of oculopharyngeal muscular dystrophy homozygotes

Objective: To assess the evolution and life expectancy in patients with oculopharyngeal muscular dystrophy (OPMD) who are homozygotes for two (GCN)13 expansions in the PABPN1 encoding gene. Background: OPMD is particularly frequent among French Canadians (FCs) and Uzbek Jews (UJs), who carry a same size, (GCN)13, PABPN1 mutation. The high rate of consanguinity among UJs together with late disease onset and normal fertility results in homozygous cases. Methods: For 15 to 20 years, we followed 4 FC and 6 UJ homozygotes with OPMD and compared them with their heterozygous parents and siblings. In addition to clinical evaluation, electrodiagnostic tests, psychological tests, and brain imaging studies were performed. Results: In all (GCN)13–(GCN)13 patients, OPMD started before age 35 years, with bilateral ptosis and dysphagia; external ophthalmoparesis and dysphonia followed within a few years, as well as weakness in proximal limb muscles. All patients had recurrent aspirations and lost weight; 4 patients required surgical interventions to alleviate dysphagia, and 5 required feeding gastrostomies. Most patients were followed by psychiatrists due to cognitive decline, recurrent depression, or psychotic episodes. Six patients died at ages 50, 51, 53, 56, 56, and 57 years. The eldest patient is now 51 years old; she is cachectic and requires special diet and psychiatric care for paranoid psychosis and uninhibited behavior. Conclusions: Oculopharyngeal muscular dystrophy progresses faster in homozygote compared with heterozygote patients. It is not restricted to the muscles, but also involves the CNS with cognitive decline and psychotic manifestations and leads to a reduced life expectancy.