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Oculopharyngeal muscular dystrophy (OPMD) is mainly characterized by ptosis and dysphagia. The genetic cause is a short expansion of a (GCN)10 repeat encoding for polyalanine in the poly(A) binding protein nuclear 1 (PABPN1) gene to (GCN)12–17 repeats. The (GCN)11/Ala11 allele has so far been described to be either a polymorphism or a recessive allele with no effect on the phenotype in the heterozygous state. Here we report the clinical and histopathological phenotype of a patient carrying a single (GCN)11/Ala11 heterozygous allele and presenting an atypical form of OPMD with dysphagia and late and mild oculomotor symptoms. Intranuclear inclusions were observed in his muscle biopsy. This suggests a dominant mode of expression of the (GCN)11/Ala11 allele associated with a partial penetrance of OPMD.

Objective: To describe a new entity of congenital muscular dystrophies caused by de novo LMNA mutations. Methods: Fifteen patients presenting with a myopathy of onset in the first year of life were subjected to neurological and genetic evaluation. Histopathological and immunohistochemical analyses were performed for all patients. Results: The 15 patients presented with muscle weakness in the first year of life, and all had de novo heterozygous LMNA mutations. Three of them had severe early-onset disease, no motor development, and the rest experienced development of a “dropped head” syndrome phenotype. Despite variable severity, there was a consistent clinical pattern. Patients typically presented with selective axial weakness and wasting of the cervicoaxial muscles. Limb involvement was predominantly proximal in upper extremities and distal in lower extremities. Talipes feet and a rigid spine with thoracic lordosis developed early. Proximal contractures appeared later, most often in lower limbs, sparing the elbows. Ten children required ventilatory support, three continuously through tracheotomy. Cardiac arrhythmias were observed in four of the oldest patients but were symptomatic only in one. Creatine kinase levels were mild to moderately increased. Muscle biopsies showed dystrophic changes in nine children and nonspecific myopathic changes in the remaining. Markedly atrophic fibers were common, most often type 1, and a few patients showed positive inflammatory markers. Interpretation: The LMNA mutations identified appear to correlate with a relatively severe phenotype. Our results further broaden the spectrum of laminopathies and define a new disease entity that we suggest is best classified as a congenital muscular dystrophy (LMNA-related congenital muscular dystrophy, or L-CMD). Ann Neurol 2008;64:177–186

Background: Heart-hand syndromes are a heterogeneous group of genetic disorders characterized by the association of congenital cardiac disease and limb deformities. Laminopathies are a group of diseases caused by mutations in the LMNA gene encoding A-type lamins. Results: We report a new LMNA mutation (c.1609-12T>G, IVS9-12 T>G) that creates a new cryptic splicing site with the retention of 11 intronic nucleotides in the mRNA. This LMNA mutation segregates with a new type of heart-hand syndrome in a previously reported family suffering from adult-onset progressive conduction system disease, atrial and ventricular tachyarrhythmias, sudden death, dilated cardiomyopathy, and brachydactyly with predominant foot involvement. Analysis of the fibroblasts of 2 affected family members identified for the first time a truncated lamin A/C protein resulting from the frame shift created by the new splicing site, together with nuclear envelope abnormalities confirming that this LMNA mutation is pathogenic. Conclusions: This new heart-hand syndrome should therefore be considered as a new kind of laminopathy. And as part of laminopathies with heart involvement, patients presenting with this phenotype and their relatives are at risk for developing sudden cardiac death and should beneficiate from appropriate LMNA genetic diagnosis.

Resume Introduction La dystrophie musculaire des ceintures de type 1B (LGMD1B), due a des mutations du gene LMNA , associe une faiblesse musculaire des ceintures a une atteinte cardiaque caracterisee par des troubles de la conduction auriculo-ventriculaire et une cardiomyopathie dilatee. Elle reste une forme peu connue de dystrophie des ceintures, et seulement 7 mutations du gene LMNA ont ete decrites comme etant responsables d’une LGMD1B. Le diagnostic clinique et genetique de cette myopathie est essentiel pour assurer la prise en charge de l’atteinte cardiaque et le conseil genetique. Patients et methodes Nous decrivons l’atteinte musculaire et cardiaque de 14 patients appartenant a 8 familles chez qui ont ete identifiees 6 mutations differentes, dont 4 nouvelles, du gene LMNA . Resultats Onze patients avaient une LGMD1B avec une atteinte scapulo-humerale et pelvi-femorale. Treize patients avaient une atteinte cardiaque. Des troubles de la conduction etaient presents chez 12 patients, et des troubles du rythme chez 9 patients. Sept patients ont beneficie de l’implantation d’un pacemaker ou d’un defibrillateur. Une transplantation cardiaque fut pratiquee dans 2 cas. Conclusion Cette etude permet de preciser les principales caracteristiques cliniques de cette affection musculaire ainsi que les premieres relations phenotype/genotype resultant de ces nouvelles observations.

Emery Dreifuss muscular dystrophy is a genetically heterogeneous disorder characterized by the clinical triad of early onset contractures, progressive muscular wasting and weakness with humeroperoneal distribution and cardiac conduction defects. Mutations in the Lamin A/C (LMNA) gene are responsible for the autosomal dominant and the autosomal recessive forms. Familiar and sporadic patients carrying mutations in the LMNA gene show high variability in the clinical symptomatology and age of onset. In this report, we describe four families harboring missense mutations in the LMNA gene and we show that the effect of mutations ranges from silent to fully penetrant. We suggest that incomplete penetrance of dominant mutations in the LMNA gene is a common feature and we emphasize the significance of mutational analysis in relatives of sporadic cases of laminopathies, as asymptomatic carriers face high risk of sudden cardiac death.

Background —The 2 genes KCNQ1 (LQT1) and HERG (LQT2), encoding cardiac potassium channels, are the most common cause of the dominant long-QT syndrome (LQTS). In addition to QT-interval prolongation, notched T waves have been proposed as a phenotypic marker of LQTS patients. Methods and Results —The T-wave morphology of carriers of mutations in KCNQ1 (n=133) or HERG (n=57) and of 100 control subjects was analyzed from Holter ECG recordings. Averaged T-wave templates were obtained at different cycle lengths, and potential notched T waves were classified as grade 1 (G1) in case of a bulge at or below the horizontal, whatever the amplitude, and as grade 2 (G2) in case of a protuberance above the horizontal. The highest grade obtained from a template defined the notch category of the subject. T-wave morphology was normal in the majority of LQT1 and control subjects compared with LQT2 (92%, 96%, and 19%, respectively, P P HERG . Conclusions —This study provides novel evidence that Holter recording analysis is superior to the 12-lead ECG in detecting G1 and G2 T-wave notches. These repolarization abnormalities are more indicative of LQT2 versus LQT1, with G2 notches being most specific and often reflecting HERG core domain missense mutations.

Life-threatening cardiac and respiratory complications are common in LMNA-related myopathies and early diagnosis is important for optimal patient care. Lamin A/C related congenital muscular dystrophy (L-CMD) is often caused by de novo mutation in LMNA, affecting a single child in a family. Germinal mosaicism is a rarer variant that can lead to two children inheriting the same new heterozygous mutation from a clinically unaffected parent. Both patterns mimic autosomal recessive (AR) inheritance and the possibility of de novo L-CMD may be forgotten since most causes of congenital muscular dystrophy follow AR inheritance. To illustrate the challenge of diagnosing L-CMD, we present a consanguineous family in which two children have early onset LMNA-related myopathy likely due to paternal germinal mosaicism. This emphasises that germinal mosaicism (and de novo mutations) for LMNA can arise in any family and direct gene sequencing is required to confirm or exclude the diagnosis.

Desmin myopathy is a heterogeneous neuromuscular disorder characterized by skeletal myopathy and cardiomyopathy, inherited mostly in an autosomal dominant pattern. We report a five generation Uruguayan family with severe cardiomyopathy and skeletal myopathy. Its most striking features are: atrial dilation, arrhythmia, conduction block and sudden death due to conduction impairment. Affected skeletal muscle shows alteration of mitochondria with paracrystallin inclusions and granulofilamentous material scattered in the muscle fibres. This family carries an unusual deletion p.E114del within the 1A rod domain of desmin. Transfected cells expressing the mutated desmin show punctuated and speckled cytoplasmic aggregates. The mutation causes a local conformational change in heptads a/d residues and charge positions. These findings lead to the hypothesis that coiled-coil interactions may be impaired, resulting in severe alterations in the desmin network. This is the first time that a mutation affecting this domain in the desmin molecule is described in a desminopathy.

Laminopathies are now recognized as a group of disorders due to mutations of the LMNA gene, which encodes A-type lamins. Primarily, mutations in LMNA have been associated to the autosomal forms of Emery-Dreifuss muscular dystrophy, a rare slowly progressive humero-peroneal muscular dystrophy accompanied by early contractures and dilated cardiomyopathy with conduction defects. LMNA mutations have been reported to be responsible for up to 10 distinct phenotypes that affect specifically either the skeletal and/or cardiac muscle, the adipose tissue, the peripheral nervous tissue, the bone tissue or more recently premature ageing. So far more than 180 different LMNA mutations have been identified in 903 individuals. The first studies of phenotype/genotype relationships revealed no dear relation between the phenotype and the type and/or the localization of the mutation, except perhaps for the globular tail domain of lamins A/C. Studies of the consequences of LMNA mutations in the skin cultured fibroblasts from the patients reveal abnormal nuclei in variable proportions, with dysmorphic nuclei exhibiting abnormal patterns of expression of B-type lamins and emerin. Finally, the development of KO and KI LMNA mice, will certainly give further insight into the pathophysiological mechanisms associated with LMNA mutations. For example, Lmna(H222P/H222P) mice harbour phenotypes reminiscent of Emery-Dreifuss muscular dystrophy.

Background: Mutations in the EMD and LMNA genes, encoding emerin and lamins A and C, are responsible for the X-linked and autosomal dominant and recessive forms of Emery–Dreifuss muscular dystrophy (EDMD). LMNA mutations can also lead to several other disorders, collectively termed laminopathies, involving heart, fat, nerve, bone, and skin tissues, and some premature ageing syndromes. Methods: Fourteen members of a single family underwent neurologic, electromyographic, and cardiologic assessment. Gene mutation and protein expression analyses were performed for lamins A/C and emerin. Results: Clinical investigations showed various phenotypes, including isolated cardiac disease (seven patients), axonal neuropathy (one patient), and a combination of EDMD with axonal neuropathy (two patients), whereas five subjects remained asymptomatic. Genetic analyses identified the coincidence of a previously described homozygous LMNA mutation (c.892C→T, p. R298C) and a new in-frame EMD deletion (c.110-112delAGA, p. delK37), which segregate independently. Analyses of the contribution of these mutations showed 1) the EMD codon deletion acts in X-linked dominant fashion and was sufficient to induce the cardiac disease, 2) the combination of both the hemizygous EMD and the homozygous LMNA mutations was necessary to induce the EDMD phenotype, 3) emerin was present in reduced amount in EMD -mutated cells, and 4) lamin A/C and emerin expression was most dramatically affected in the doubly mutated fibroblasts. Conclusions: This highlights the crucial role of lamin A/C–emerin interactions, with evidence for synergistic effects of these mutations that lead to Emery–Dreifuss muscular dystrophy as the worsened result of digenic mechanism in this family.

Background Mutations of the LMNA gene, encoding the nuclear envelope proteins lamins A and C, have been associated with 7 distinct pathologic conditions. Objective To report 5 cases with the same missense mutation in exon 6 of the LMNA gene, resulting in an E358K substitution in the central rod domain. Design Case report. Setting Three muscle centers in England. Patients Five patients with missense mutations of the LMNA gene. Results All 5 individuals had muscle involvement, but the onset, severity, distribution of muscle weakness, and presence of associated features were highly variable. Three patients had humeroperoneal distribution of weakness and typical features of Emery-Dreifuss muscular dystrophy. Two other patients showed additional novel features. One had congenital onset and predominant axial weakness, with poor neck control and inability to sit independently at the age of 21 months. Another patient presented in childhood with an unusual pattern of muscle weakness, short stature, and midface hypoplasia with striking fat accumulation around the face and neck, in contrast to wasting of adipose tissue and muscle in the limbs. She developed both respiratory failure and cardiac arrhythmias in her late 20s. Conclusion Our cases expand the clinical spectrum associated with mutations in the LMNA gene and further illustrate the overlapping phenotypes of the laminopathies.

Mutations in the lamin A/C gene are found in Emery-Dreifuss muscular dystrophy, limb girdle muscular dystrophy with cardiac conduction disturbances, dilated cardiomyopathy with conduction system disease, and familial partial lipodystrophy. Cases with lamin A/C mutations presenting with lipodystrophy in combination with cardiac and/or skeletal muscle abnormalities are described.

Abstract —The voltage-gated K + channel KVLQT1 is essential for the repolarization phase of the cardiac action potential and for K + homeostasis in the inner ear. Mutations in the human KCNQ1 gene encoding the α subunit of the KVLQT1 channel cause the long-QT syndrome (LQTS). The autosomal dominant form of this cardiac disease, the Romano-Ward syndrome, is characterized by a prolongation of the QT interval, ventricular arrhythmias, and sudden death. The autosomal recessive form, the Jervell and Lange-Nielsen syndrome, also includes bilateral deafness. In the present study, we report the entire genomic structure of KCNQ1 , which consists of 19 exons spanning 400 kb on chromosome 11p15.5. We describe the sequences of exon-intron boundaries and oligonucleotide primers that allow polymerase chain reaction (PCR) amplification of exons from genomic DNA. Two new (CA) n repeat microsatellites were found in introns 10 and 14. The present study provides helpful tools for the linkage analysis and mutation screening of the complete KCNQ1 gene. By use of these tools, five novel mutations were identified in LQTS patients by PCR–single-strand conformational polymorphism (SSCP) analysis in the C-terminal part of KCNQ1 : two missense mutations, a 20-bp and 1-bp deletions, and a 1-bp insertion. Such mutations in the C-terminal domain of the gene may be more frequent than previously expected, because this region has not been analyzed so far. This could explain the low percentage of mutations found in large LQTS cohorts.

The LMNA gene encodes two nuclear envelope proteins, lamins A and C, derived from alternative splicing. First identified in autosomal dominant Emery-Dreifuss muscular dystrophy (AD-EDMD),1 mutations in this gene are implicated in up to seven diseases including autosomal recessive EDMD (AR-EDMD),2 limb-girdle muscular dystrophy type 1B (LGMD1B),3 dilated cardiomyopathy with conduction defects (DCM-CD),4,5 autosomal dominant partial lipodystrophy of Dunnigan type,6 autosomal recessive axonal Charcot-Marie-Tooth disease (AR-CMT2),7 mandibuloacral dysplasia,8 and Hutchinson-Gilford progeria syndrome.9,10 In addition, some patients appear to have a combination of these different phenotypes11,12 or a clinical variant including skin abnormalities.13 To extend the clinical spectrum of laminopathies, we report a previously undescribed dominant missense mutation, E33D, identified in LMNA and clinically characterised by the combination of axonal neuropathy with myopathic features, cardiac disease including dilated cardiomyopathy, conduction disturbances and arrhythmia, and leuconychia. The LMNA gene is therefore the first gene implicated in both autosomal dominant and recessive forms of CMT2. The pedigree of a white family originating from the south west of France is shown in fig 1. The index case (II-5) and his affected daughter (III-13) were neurologically and cardiologically assessed by one of our team; only partial information was available for other affected members through questioning of patient III-13. The clinical features of all the affected members are shown in table 1. The results of nerve electrophysiological examination of patients II-5 and III-13 are shown in table 2. A muscle CT scan performed for patient II-5 showed wasting and marked fatty infiltration predominating in paraspinal, vasti, hamstring, and gastrocnemius muscles (fig 2). Fig 3 shows the fingernails of patients II-5 and III-13, exhibiting leuconychia. View this table: Table 1 Clinical features of the affected family members View this table: Table 2 Electrophysiological study of patients II-5 and III-13 Figure 1 Pedigree of the family. Arrow …