Novel OCTN2 mutations: No genotype–phenotype correlations: Early carnitine therapy prevents cardiomyopathy

Primary systemic carnitine deficiency or carnitine uptake defect (OMIM 212140) is a potentially lethal, autosomal recessive disorder characterized by progressive infantile‐onset cardiomyopathy, weakness, and recurrent hypoglycemic hypoketotic encephalopathy, which is highly responsive to L ‐carnitine therapy. Molecular analysis of the SLC22A5 (OCTN2) gene, encoding the high‐affinity carnitine transporter, was done in 11 affected individuals by direct nucleotide sequencing of polymerase chain reaction products from all 10 exons. Carnitine uptake (at Km of 5 μM) in cultured skin fibroblasts ranged from 1% to 20% of normal controls. Eleven mutations (delF23, N32S, and one 11‐bp duplication in exon 1; R169W in exon 3; a donor splice mutation [IVS3+1 G > A] in intron 3; frameshift mutations in exons 5 and 6; Y401X in exon 7; T440M, T468R and S470F in exon 8) are described. There was no correlation between residual uptake and severity of clinical presentation, suggesting that the wide phenotypic variability is likely related to exogenous stressors exacerbating carnitine deficiency. Most importantly, strict compliance with carnitine from birth appears to prevent the phenotype. © 2002 Wiley‐Liss, Inc.     

阿霉素性心肌病之心肌线粒体酶的细胞化学研究

阿霉素性心肌病之心肌线粒体SDH和CCO的细胞化学观察发现,多数线粒体的酶活性较弱,少数较强或中等,并与ADR的累积用量和心肌损伤程度有关。作者认为SDH和CCO活性降低,线粒体能量代谢障碍在ADR引起心肌病的过程中起着重要作用。     

No evidence for humoral autoimmunity against cardiomyocytes,adrenergic or muscarinic receptors in patients with Tako-Tsubo cardiomyopathy

Background

An association between Tako-Tsubo cardiomyopathy (TTC) and underlying malignancies has been observed, suggesting that TTC might be the consequence of paraneoplastic phenomena. This study investigates the presence of autoantibodies against cardiomyocytes as well as adrenergic (β₁, β₂) and muscarinic (M2) receptors in patients with TTC.

Severe dilated cardiomyopathy as a consequence of Ecstasy intake

Dilated cardiomyopathy (DCM) is one of the most common causes of heart failure with a prevalence of 1:2500. There are several primary and secondary etiologic factors, including gene mutations, infection agents, particularly viruses, toxins, autoimmune, and systemic disorders, and pheochromocytoma, neuromuscular, metabolic, mitochondrial, and nutritional disorders. However, a precise diagnosis can be reached only in no more than 50% of all cases. Herein, we report a rare case of hepatic damage and severe DCM as a consequence of relatively popular socially used narcotic-Ecstasy (3,4-methylenedioxy-N-methylamphetamine [MDMA]).     

Loss of lamin A/C expression revealed by immuno-electron microscopy in dilated cardiomyopathy with atrioventricular block caused by<Emphasis Type="Italic"> LMNA</Emphasis> gene defects

Mutations of the LMNA gene encoding the lamin A and C nuclear envelope proteins cause an autosomal dominant form of dilated cardiomyopathy (DCM) with atrioventricular block (AVB). The aim of this study was to investigate ultrastructural nuclear membrane changes by conventional electron microscopy and protein expression by immuno-electron microscopy in the heart of patients with DCM and AVB due to LMNA gene mutations. Four immunohistochemical techniques were used: pre-embedding and post-embedding in Epon-Araldite resin and London Resin White (LRW), with and without silver enhancement. Parallel light microscopy immunohistochemistry studies were performed. Conventional electron microscopy showed a loss of integrity of the myocyte nuclei with blebs of the nuclear membrane, herniations and delamination of the nuclear lamina and nuclear pore clustering. Post-embedding LRW was the most informative technique for morphology and immuno-labelling. Immuno-labelling was almost absent in the nuclear envelope of patients with LMNA gene mutations, but intensely present in controls. The loss of labelling selectively affected myocyte nuclei; the endothelial cell nuclei were immunostained in patients and controls. Light immunohistochemistry confirmed the results. These findings confirm the hypothesis that LMNA gene defects are associated with a loss of protein expression in the selective compartment of non-cycling myocyte nuclei.     

Genomic structure and eight novel exonic polymorphisms of the human N-cadherin gene

 Analysis of the detailed genomic structure of human N-cadherin revealed that the 16-exon gene is more than 72 kb in length and that it consists of a mosaic of exons. Five repeated cadherin domains, a transmembrane domain, and a cytoplasmic domain are encoded by exons 4 to 13, 13 and 14, and 14 to 16, respectively. A search for molecular variants in the entire coding region in 96 Japanese individuals resulted in the identification of eight sequence polymorphisms including three CCT- or GCC-type trinucleotide repeat polymorphisms adjacent to the initiation codon and five other novel single-nucleoticle polymorphisms (SNPs) in the coding region. Three of the five SNPs accompanied an amino acid substitution: Ala118Thr, Ala826Thr, and Asn845Ser. Knowlege of the fine gene structure and eight novel polymorphisms will be useful for the genetic study of the role of N-cadherin in diseases involving cell adhesion in the brain and in cardiomyocytes. Received: January 23, 2002 / Accepted: March 12, 2002     

Structural and functional analysis of a new desmin variant causing desmin‐related myopathy

Desmin‐related myopathy is a familial or sporadic disease characterized by skeletal muscle weakness and cardiomyopathy as well as the presence of intracytoplasmic aggregates of desmin‐reactive material in the muscle cells. Previously, two kinds of deletions and eight missense mutations have been identified in the desmin gene and proven to be responsible for the disorder. The present study was conducted to determine structural and functional defects in a pathogenic desmin variant that caused a disabling disorder in an isolated case presenting with distal and proximal limb muscle weakness and cardiomyopathy. We identified a novel heterozygous Q389P desmin mutation located at the C‐terminal part of the rod domain as the causative mutation in this case. Transfection of desmin cDNA containing the patient’s mutation into C2.7, MCF7, and SW13 cells demonstrated that the Q389P mutant is incapable of constructing a functional intermediate filament network and has a dominant negative effect on filament formation. We conclude that Q389P mutation is the molecular event leading to the development of desmin‐related myopathy. Hum Mutat 18:388–396, 2001. © 2001 Wiley‐Liss, Inc.     

Duchenne muscular dystrophy and idiopathic hyperCKemia segregating in a family

A 7-month-old boy with gross motor delay and failure to thrive presented with rhabdomyolysis following an acute asthmatic episode. During hospitalization an electrocardiographic conversion to a Wolff-Parkinson-White type 1 (WPW) pattern took place. Duchenne muscular dystrophy (DMD) was suspected based on elevated creatine kinase (CK) serum levels, muscle biopsy, and family history. The diagnosis was confirmed by molecular analysis, which documented a deletion corresponding to cDNA probe 1-2a in the dystrophin gene, in the propositus and in an affected male cousin of his mother. “Idiopathic” hyperCKemia was found in the propositus, his father, and 5 of his relatives. We suggest that the unusually early and severe manifestations of DMD in this patient may be related to the coincidental inheritance of the maternal DMD gene and of a paternal gene, causing hyperCKemia. © 1995 Wiley-Liss, Inc.     

Successive infection of coxsackievirus B3 and encephalomyocarditis virus: an animal model of chronic myocarditis.

Successive infection of coxsackievirus B3 and encephalomyocarditis virus was investigated as a disease model of chronic myocarditis. Four-week-old C3H/He mice were inoculated with coxsackievirus B3 and then inoculated with encephalomyocarditis virus at 8 weeks old. The hearts were evaluated on histopathological changes compared with those of non-infected mice and mice infected with either virus alone. At 10 weeks old, the hearts of the mice infected successively with both viruses showed co-existence of fibrosis surrounding calcified lesions and marked cellular infiltration with myocardial necrosis. These findings resembled chronic active myocarditis in humans, unlike the lesions due to either virus alone. At 12 weeks old, the hearts of all the infected mice showed fibrosis with scarce cellular infiltration. The successively infected hearts also showed a significantly higher heart weight to body weight ratio than that of the non-infected control mice, and localized wall thinning in the damaged regions. Thus, we conclude that successive infection additively causes myocardial damage that resembles chronic myocarditis and may produce a heart condition similar to dilated cardiomyopathy.     

Cardiomyopathy in congenital complete lipodystrophy

Molecular genetic studies have pointed to a relationship between congenital lipodystrophy syndromes and some cardiac disorders. For instance, mutations in LMNA cause either lipodystrophy or cardiomyopathy, indicating that different mutations in the same gene can produce these clinical syndromes. The present authors describe a 10-year-old female with Berardinelli-Seip congenital complete lipodystrophy (MIM 606158) caused by homozygosity for a frameshift mutation in BSCL2. In addition to the typical attributes of complete lipodystrophy, this subject had hypertrophic cardiomyopathy diagnosed in the first year of her life; its progress has been followed with non-invasive imaging. The mechanism underlying the hypertrophic cardiomyopathy in complete lipodystrophy is unclear. It may result from a direct effect of the mutant gene or it might be secondary to the effects of hyperinsulinemia on cardiac development. The variability of the associated cardiomyopathy in patients with complete generalized lipodystrophy may be caused by differential effects of mutations in the same gene or of mutations in different genes which underlie the lipodystrophy phenotype.