G.P.5.05 A novel mutation in a French–Canadian family with LGMD1B

Abstracts / Neuromuscular Disorders 17 (2007) 764–900 G.P.5.05 A novel mutation in a French–Canadian family with LGMD1B Dupre, N. 1,*; Chrestian, N. 1; Valdmanis, P. 2; Rouleau, G. 2; Echahidi, N. 1; Champagne, J. 1; Brunet, D. 1; Gould, P. 1 1 Laval University, Quebec, Canada; 2 Universite´ de Montreal, Montreal, Canada Background: Limb girdle muscular dystrophy type 1b (LGMD1B) is an autosomal dominant form of LGMD characterized by late onset proximal muscle involvement associated with cardiac complications such as atrioventricular conduction blocks (AVB), dilated cardiomyopathy, and sudden death. Objectives: We identified a proband with the LGMD 1B phenotype that carried a new mutation in the LMNA gene and sought to define the full phenotypic spectrum of this mutation. Method: All 13 at risk relatives of the proband were evaluated clinically by a neurologist and a cardiologist, and underwent basic work-up (echocardiogram, electrocardiogram, Holter monitoring). Genetic testing was performed. Muscle biopsy of a deceased family member was available. A blood sample from the proband was also obtained for RNA study. Results: Of the 13 at risk relatives, seven carried the (IVS9-3C>G) LMNA gene mutation. This mutation was not found in 100 ethnically-matched normal controls. Of these seven carriers, three were symptomatic and 4 were asymptomatic. The index case had significant hip-girdle weakness. She presented at age 40 with symptomatic AVB leading to pacemaker implantation. Her brother had a pacemaker implanted for paroxysmal AVB at age 42 and showed mild hip-girdle weakness. Another younger symptomatic relative had a pacemaker implanted at age 28. He showed no muscle weakness. The one available muscle biopsy demonstrated a normally expressed lamin A/C protein, localized at the nuclear envelope. The cDNA sequencing on the proband revealed a 319-bp product lacking LMNA exon 10 along with a normal product of 409-bp. The RNA study therefore revealed a loss of exon 10 transcription caused by the IVS9-3C to G splicing mutation. Conclusions: This study describes the phenotype of a family with a novel LMNA mutation that shows cardiac predilection, with mild to moderate hip-girdle weakness. In this family, early cardiac symptoms generally lead to pacemaker implantation in middle age. doi:10.1016/j.nmd.2007.06.128

G.P.5.06 LMNA p.R644C: Pathogenic mutation of low penetrance, disease modifier or polymorphism? Auer-Grumbach, M. 1,*; Fischer, C. 1; Duong, N. 2; Huebner, A. 3; John, E. 1; Wagner, K. 1; Speicher, M. 1; Wehnert, M. 2 1 Medical University of Graz, Institute of Human Genetics, Graz, Austria; 2 University of Greifswald, Institute of Human Genetics, Greifswald, Germany; 3 Dresden University of Technology, Faculty of Medicine Carl Gustav Carus, Dresden, Germany Autosomal dominant Emery–Dreifuss muscular dystrophy (ADEDMD) is caused by mutations in the LMNA gene and clinically characterised by early onset of skeletal muscle weakness, joint contractures and cardiac arrythmias including dilated cardiomyopathy. There is a highly variable inter and intrafamilial expression of the clinical phenotype. Moreover, mutations in LMNA may result in at least 11 distinct neuromuscular and non-neuromuscular conditions plus some clinically overlapping forms. We identified a family with two male patients affected by EDMD. In addition, one brother had pes cavus foot deformity since birth and sensory motor neuropathy in the lower limbs mimicking a mild CharcotMarie-Tooth (CMT) phenotype. Another brother and the parents were normal on clinical and neurophysiological examination. Linkage analysis excluded most subtypes of limb girdle muscular dystrophy but suggested possible linkage to the AD-EDMD locus on chromosome 1. Sequencing of the LMNA gene detected a p.R644C LMNA mutation in the two EDMD patients as well as in the unaffected mother and in the healthy

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brother but was not present in the brother exhibiting the mild CMT phenotype. The absence of p.R644C mutation has been demonstrated in 250 individuals of a reference population. No DNA aberrations were found in the STA (emerin) gene. All family members, carrying the LMNA p.R644C mutation had mildly to moderately elevated CK levels but no signs of cardiac disease. Interestingly, this mutation has previously been associated to such variable phenotypes as EDMD, dilated cardiomyopathy with conduction disturbances, hypertrophic cardiomyopathy with myopathy, limb-girdle muscular dystrophy type 1B and progeria. Additionally, two heterozygous carriers of p.R644C were asymptomatic. What is more, p.R644C in combination with mutations in STA and desmin increases the severity of EDMD. Thus, as supported by our finding too, p.R644C is likely to act as a modifier. doi:10.1016/j.nmd.2007.06.129

G.P.5.07 Nuclear changes in muscular dystrophy associated with nuclear envelopathy Hayashi, Y. *; Astejada, M.; Park, Y.; Nonaka, I.; Noguchi, S.; Nishino, I. National Institute of Neuroscience, NCNP, Tokyo, Japan Nuclear envelopathy is a group of disorders caused by mutations in the genes for nuclear envelope proteins. Both Emery–Dreifuss muscular dystrophy (EDMD) and limb girdle muscular dystrophy (LGMD) are caused by mutations in the genes encoding lamin A/C and emerin. To know the detailed morphological abnormalities of nuclei, we examined muscle specimens from muscular dystrophy patients associated with nuclear envelopathy including seven emerinopathy and seven laminopathy. We also examined cultured skin fibroblasts from 5 patients (three emerinopathy and two laminopathy). In muscle specimen from one laminopathy patients, markedly vacuolated myonuclei were seen together with rimmed vacuoles. Another young laminopathy patient had also vacuolated myonuclei under electron microscope. Cultured fibroblasts revealed increased number of the altered shaped nuclei compared to the cells from controls, with accumulation of the proteins including LAP2 and BAF. Muscles from patients with nuclear envelopathy can show marked disorganized nuclear morphology. Fragile nuclear membrane associated with abnormal accumulation of the proteins can closely associated with pathomechanisms of this disorder. doi:10.1016/j.nmd.2007.06.130

G.P.5.08 PCNA staining pattern is altered in Emery–Dreifuss fibroblasts Zamparelli, A. 1,*; Lattanzi, G. 1; Colomer, J. 2; Merlini, L. 3; Maraldi, N. 4; Sabatelli, P. 1 1 IGM-CNR, Unit of Bologna c/o IOR, Bologna, Italy; 2 Unitat de Patologia Neuromuscular, Servei de Neurologia Esplugues, Barcelona, Spain; 3 Department of Medical Genetics, Neuromuscular Unit, University of Ferrara, Ferrara, Italy; 4 Laboratory of Cell Biology and Electron Microscopy, Istituti Ortopedici Rizzoli, Bologna, Italy Lamin A and C are major component of the nuclear lamina, a thin electron-dense layer located at the inner surface of the nuclear membrane and closely associated with chromatin. The laminA/C gene mutations cause several diseases, including Emery–Dreifuss muscular dystrophy (EDMD). Several roles for the nuclear lamina have been proposed, including its involvement in nuclear structure, gene expression, cell-cycle progression, and DNA replication. We have analysed primary cultures of skin fibroblasts from two patients harbouring lamin A/C mutations. A subpopulation of cells showed a honeycomb pattern for lamin A/C distribution. In order to investigate the relationship between this altered lamin