Gene/Protein Disease Symptom Drug Enzyme Compound
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Oculopharyngeal muscular dystrophy is a hereditary, autosomal dominant, slowly progressive disorder with onset that occurs during middle age. Major symptoms are ptosis and dysphagia resulting primarily from selectively involved levator palpebrae and the pharyngeal muscles. Progressive, usually symmetrical blepharoptosis, with or without dysphagia, appears during middle age. Muscular weakness in the limbs can be noted in some patients. The guidelines for surgery in myopathic ptosis are conservative in view of the increased risk of postoperative corneal complications. However, orbicularis function remains intact in oculopharyngeal muscular dystrophy; therefore, corrective surgery is performed in most patients. This report describes four cases of ptosis correction in patients with oculopharyngeal muscular dystrophy in one family. The frontalis action was very poor to qualify for frontalis transfer; therefore, the authors performed moderate to large levator resection in all patients. The follow-up results 5 years postoperatively are promising to date and all the patients are satisfied with the results.
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PMID:Correction of blepharoptosis in oculopharyngeal muscular dystrophy. 1237 Jun 50

Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disorder characterized by progressive eyelid drooping (ptosis), swallowing difficulties (dysphagia), and proximal limb weakness. The autosomal dominant form of this disease is caused by expansions of a (GCG)6 repeat to (GCG)8-13 in the PABPN1 gene. These mutations lead to the expansion of a polyalanine stretch from 10 to 12-17 alanines in the N-terminal domain of PABPN1. Mutated PABPN1 (mPABPN1) induces the formation of muscle intranuclear inclusions that are thought to be the hallmark of this disease. In this review, we discuss: 1) OPMD genetics and PABPN I function studies; 2) diseases caused by polyalanine expansions and cellular polyalanine toxicity; 3) mPABPN1-induced intranuclear inclusion toxicity; 4) role of oligomerization of mPABPNI in the formation and toxicity of OPMD intranuclear inclusions and; 5) recruitment of subcellular components to the OPMD inclusions. We present a potential molecular mechanism for OPMD pathogenesis that accounts for these observations.
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PMID:Progress in understanding the pathogenesis of oculopharyngeal muscular dystrophy. 1261 77

Autosomal dominant oculopharyngeal muscular dystrophy (OPMD) is a late-onset disorder characterized clinically by progressive ptosis, dysphagia and limb weakness, and by unique intranuclear inclusions in the skeletal muscle fibers. The disease is caused by the expansion of a 10-alanine stretch to 12-17 alanine residues in the poly(A)-binding protein, nuclear 1 (PABPN1; PABP2). While PABPN1 is a major component of the inclusions in OPMD, the exact cause of the disease is unknown. To elucidate the molecular mechanism and to construct a useful model for therapeutic trials, we have generated transgenic mice expressing the hPABPN1. Transgenic mice lines expressing a normal hPABPN1 with 10-alanine stretch did not reveal myopathic changes, whereas lines expressing high levels of expanded hPABPN1 with a 13-alanine stretch showed an apparent myopathy phenotype, especially in old age. Pathological studies in the latter mice disclosed intranuclear inclusions consisting of aggregated mutant hPABPN1 product. Furthermore, some TUNEL positive nuclei were shown around degenerating fibers and a cluster of it in the lesion in necrotic muscle fibers. Interestingly, the degree of myopathic changes was more prominent in the eyelid and pharyngeal muscles. Further, muscle weakness in the limbs was apparent as shown by the fatigability test. Nuclear inclusions seemed to develop gradually with aging, at least after 1 week of age, in model mouse muscles. We established the first transgenic mouse model of OPMD by expressing mutated PABPN1, and our model mice appear to have more dramatic alternations in myofiber viability.
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PMID:Myopathy phenotype in transgenic mice expressing mutated PABPN1 as a model of oculopharyngeal muscular dystrophy. 1464 3

We report a 75-year-old Spanish-American woman who received a diagnosis of oculopharyngeal muscular dystrophy after presenting with ptosis and dysphagia. She also complained of snoring and daytime somnolence, and was found to have obstructive sleep apnea (OSA) syndrome attributable to her neuromuscular disorder. This is the first report of OSA syndrome complicating typical, adult-onset oculopharyngeal muscular dystrophy, and should prompt the evaluation of other such patients for sleep-disordered breathing.
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PMID:Obstructive sleep apnea syndrome complicating oculopharyngeal muscular dystrophy. 1471 63

We reported a 52-year-old woman with oculopharyngeal muscular dystrophy (OPMD) harboring expanded (GCG) 13 mutation of the poly (A) binding protein 2 gene. She presented not only ptosis and dysphagia but distal dominant muscle atrophy in four extremities. CT demonstrated distal muscle atrophy with marked fat replacement in the biceps femoris, semitendinosus, membraneous, soleus, and gastrocnemius muscles. Although OPMD is considered to be a muscle disease, this patient showed even neurogenic features in the electrophysiological and pathological findings. Although previous reports indicate that OPMD is genetically homogeneous disease, some cases with OPMD may show some atypical features associated with neurogenic involvement.
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PMID:[Preferential distal muscle involvement in case of oculopharyngeal muscular dystrophy with (GCG) 13 expansion]. 1472 64

Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant late-onset neuromuscular degenerative disease characterised by proximal muscle weakness, ptosis and swallowing difficulty. The causative genetic abnormality is an expansion consisting of 2-7 additional base triplets in a repeat sequence in exon 1 of the PABPN1 (PABP2) gene and results in an increase in length of the polyalanine tract in the PABPN1 protein from 10 to 12-17 residues. The expansions are stable through meiosis and mitosis suggesting a different mechanism of mutation from that of most other triplet repeat mutations. Most reports describe OPMD expansions as consisting of multiples of a GCG sequence. However, some studies have detected GCA interspersions. We have analysed 86 OPMD patients with a PABPN1 gene expansion, including three compound heterozygotes, and have identified 13 different types of expansion mutation, six of which contain GCA and GCG and almost all of which are consistent with a mutational mechanism of unequal recombination.
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PMID:Oculopharyngeal muscular dystrophy (OPMD): analysis of the PABPN1 gene expansion sequence in 86 patients reveals 13 different expansion types and further evidence for unequal recombination as the mutational mechanism. 1564 84

There has been controversy whether oculopharyngodistal myopathy (OPDM) commonly seen in Japan is a distinct disease entity or a variant of oculopharyngeal muscular dystrophy (OPMD) initially described in French-Canadians and has since been reported in other ethnic groups. Both diseases have autosomal dominant inheritance and OPDM patients are clinically similar to OPMD with slowly progressive ptosis, ophthalmoplegia and dysphagia except that most of the former usually have distal as opposed to proximal weakness and most of them are genetically different from the latter The authors report here 2 siblings with clinical features of OPDM. This entity is rare outside Japan and this is the first family to be reported from Thailand
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PMID:Oculopharyngodistal myopathy in a Thai family. 1582 51

The muscular dystrophies are a heterogeneous group of disorders for which there are currently no cures. Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant late-onset, progressive disease that generally presents in the fifth or sixth decade with dysphagia, ptosis and proximal limb weakness. OPMD is caused by the abnormal expansion of a (GCG)n trinucleotide repeat in the coding region of the poly-(A) binding protein nuclear 1 (PABPN1) gene. In unaffected individuals, (GCG)6 codes for the first six alanines in a homopolymeric stretch of ten alanines. In most individuals with OPMD this (GCG)6 repeat is expanded to (GCG)8-13, leading to a stretch of 12-17 alanines in mutant PABPN1. PABPN1 with an expanded polyalanine tract forms aggregates consisting of tubular filaments within the nuclei of skeletal muscle fibers. We have developed a transgenic mouse model of OPMD that manifests progressive muscle weakness accompanied by intranuclear aggregates and TUNEL-stained nuclei in skeletal muscle fibers. The onset and severity of these abnormalities were substantially delayed and attenuated by doxycycline treatment, which may exert its therapeutic effect by reducing aggregates and by distinct antiapoptotic properties. Doxycycline may represent a safe and feasible therapeutic for this disease.
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PMID:Doxycycline attenuates and delays toxicity of the oculopharyngeal muscular dystrophy mutation in transgenic mice. 1586 13

We report a sporadic case of a female patient with oculopharyngeal muscular dystrophy (OPMD). Her father died at age 86 and mother at age 74. There was no familial occurrence of the disease. The patient initially developed a nasal voice at age 66. Neurological examinations on admission at age 72 revealed bilateral ptosis, a limitation of ocular movement without diplopia, dysphagia, and proximal muscle weakness. Serum creatine kinase level was slightly increased. Biopsied muscle specimens showed variation in fiber size as well as the occasional presence of rimmed vacuoles. On the basis of these clinical and laboratory findings, we suspected a diagnosis of OPMD, although a family history was absent. To confirm the diagnosis of OPMD, we performed a gene analysis for poly A binding protein, nuclear 1 (PABPN1; PABP2), which revealed a mild expansion of GCG repeat (8 repeats) as a heterozygous state. Clinical features of the patient were consistent with those in a previous literature reporting that patients carrying (GCG)8 repeat as a heterozygous state show a relatively late onset and a mild phenotype. The case of this patient emphasizes the importance of the PABPN1 gene analysis for patients showing muscular weakness involving oculopharyngeal and proximal limb muscles even when a familial occurrence of the disease is not apparent.
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PMID:[A late-onset case of oculopharyngeal muscular dystrophy carrying a (GCG)8 repeat expansion in the PAPBN1 gene]. 1602 69

Oculopharyngeal muscular dystrophy (OPMD) is a late-onset polyalanine disorder characterized clinically by progressive ptosis, dysphagia, and limb weakness and pathological hallmarked by unique intranuclear inclusions in the muscles. It is caused by heterozygous expansion of a 10-alanine stretch to 12-17 alanine residues in the N-terminus of the poly(A)-binding protein, nuclear 1 (PABPN1). Although PABPN1 is a major component of the inclusions in OPMD, the associated pathogenic mechanism is undetermined. No animal models of OPMD have been discovered in nature; therefore, we generated transgenic mice expressing human PABPN1 (hPABPN1) using a chicken beta-actin (CAG) promoter. While transgenic mice lines expressing normal hPABPN1 did not show myopathic changes, lines expressing high levels of expanded hPABPN1 with a 13-alanine stretch showed myopathy phenotype with aging. The latter mice disclosed intranuclear inclusions consisting of aggregated mutant hPABPN1 and scattered rimmed vacuoles restricted in the muscles. In particular, the nuclear inclusions closely resembled those of OPMD muscles on electron microscopy, and myopathic changes were more prominent in the eyelid and pharyngeal muscles. The results demonstrated that we had established the first transgenic OPMD model mouse. Recently, two other transgenic mice expressing mutated hPABPN1 with a 17-alanine stretch have been generated; however, the transgenic mouse using its natural promoter did not show myopathy phenotype, and the other using the human skeletal actin (HSA1) promoter disclosed quite different intranuclear inclusions from those of human OPMD muscles. Our transgenic OPMD model mouse appears to have more dramatic alterations in myofiber viability, but is useful for elucidating of molecular mechanisms and establishing therapeutic trials.
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PMID:Animal model of oculopharyngeal muscular dystrophy. 1655 Sep 22


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