A novel mutation of the LMNA gene in a family with dilated cardiomyopathy, conduction system disease, and sudden cardiac death of young females

The LMNA gene, which encodes the nuclear envelope protein lamin A/C, is considered to be the most common autosomal disease gene associated with familial dilated cardiomyopathy. To date, each mutation of the LMNA gene has been associated with a specific disease phenotype. Clinical data, family histories, and blood samples were collected from 27 biological members of a family with dilated cardiomyopathy, prominently occurring as heart failure and conduction system disease with a high incidence of sudden cardiac death in young females. Twelve exons of the LMNA gene were screened for nucleotide alterations. A novel insertion mutation (nucleotide 1526insA, amino acid T510Y) in exon nine of the LMNA gene was identified in seven subjects (7/27, 25.9 %). This reveals that the LMNA gene insertion mutation (T510Y frameshift mutation) can cause dilated cardiomyopathy, conduction system disease, and sudden cardiac death without skeletal myopathy, clinically manifested with early onset, severe symptoms, and poor prognosis.     

A nonsense mutation in the optic atrophy 3 gene (OPA3) causes dilated cardiomyopathy in Red Holstein cattle

Cardiomyopathies are severe degenerative disorders of the myocardium that lead to heart failure. During the last three decades bovine dilated cardiomyopathy (BDCMP) was observed worldwide in cattle of Holstein-Friesian origin. In the Swiss cattle population BDCMP affects Fleckvieh and Red Holstein breeds. The heart of affected animals is enlarged due to dilation of both ventricles. Clinical signs are caused by systolic dysfunction and affected individuals die as a result of severe heart insufficiency. BDCMP follows an autosomal recessive pattern of inheritance and the disease-causing locus was mapped to bovine chromosome 18 (BTA18). In the present study we describe the successful identification of the causative mutation in the OPA3 gene located on BTA18 that was previously reported to cause 3-methylglutaconic aciduria type III in Iraqi-Jewish patients. We demonstrated conclusive genetic and functional evidence that the nonsense mutation c.343C>T in the bovine OPA3 gene causes the late-onset dilated cardiomyopathy in Red Holstein cattle.     

Whole‐exome sequencing identifies a novel mutation of GPD1L (R189X) associated with familial conduction disease and sudden death

Cardiac conduction disease (CCD) is a serious disorder and the leading cause of mortality worldwide. It is characterized by arrhythmia, syncope or even sudden cardiac death caused by the dysfunction of cardiac voltage‐gated channel. Previous study has demonstrated that mutations in genes encoding voltage‐gated channel and related proteins were the crucial genetic lesion of CCD. In this study, we employed whole‐exome sequencing to explore the potential causative genes in a Chinese family with ventricular tachycardia and syncope. A novel nonsense mutation (c.565C>T/p.R189X) of glycerol‐3‐phosphate dehydrogenase‐like (GPD1L) was identified and co‐segregated with the affected family members. GPD1L is a crucial interacting protein of SCN5A, a gene encoded sodium channel α‐subunit Na_v1.5 and mainly associated with Brugada syndrome (BrS). The novel mutation (c.565C>T/p.R189X) may result in a premature stop codon at position 189 in exon 4 of the GPD1L gene and lead to functional haploinsufficiency of GPD1L due to mRNA carrying this mutation will be degraded by nonsense‐mediated mRNA decay, which has been confirmed by Western blot in HEK293 cells transfected HIS‐GPD1L plasmid. The levels of GPD1L decreasing may disturb the function of Na_v1.5 and induce arrhythmia and syncope in the end. In conclusion, our study not only further supported the important role of GPD1L in CCD, but also expanded the spectrum of GPD1L mutations and will contribute to the genetic diagnosis and counselling of families with CCD.     

Functional analysis of a troponin I (R145G) mutation associated with familial hypertrophic cardiomyopathy.

Familial hypertrophic cardiomyopathy has been associated with several mutations in the gene encoding human cardiac troponin I (HCTnI). A missense mutation in the inhibitory region of TnI replaces an arginine residue at position 145 with a glycine and cosegregates with the disease. Results from several assays indicate that the inhibitory function of HCTnI(R145G) is significantly reduced. When HCTnI(R145G) was incorporated into whole troponin, Tn(R145G) (HCTnT small middle dotHCTnI(R145G) small middle dotHCTnC), only partial inhibition of the actin-tropomyosin-myosin ATPase activity was observed in the absence of Ca(2+) compared with wild type Tn (HCTnT small middle dotHCTnI small middle dotHCTnC). Maximal activation of actin-tropomyosin-myosin ATPase in the presence of Ca(2+) was also decreased in Tn(R145G) when compared with Tn. Using skinned cardiac muscle fibers, we determined that in comparison with the wild type complex 1) the complex containing HCTnI(R145G) only inhibited 84% of Ca(2+)-unregulated force, 2) the recovery of Ca(2+)-activated force was decreased, and 3) there was a significant increase in the Ca(2+) sensitivity of force development. Computer modeling of troponin C and I variables predicts that the primary defect in TnI caused by these mutations would lead to diastolic dysfunction. These results suggest that severe diastolic dysfunction and somewhat decreased contractility would be prominent clinical features and that hypertrophy could arise as a compensatory mechanism.     

A missense mutation (Trp86----Arg) in exon 3 of the lipoprotein lipase gene: a cause of familial chylomicronemia.

We have investigated a patient of English ancestry with familial chylomicronemia caused by lipoprotein lipase (LPL) deficiency. DNA sequence analysis of all exons and intron-exon boundaries of the LPL gene identified two single-base mutations, a T----C transition for codon 86 (TGG) at nucleotide 511, resulting in a Trp86----Arg substitution, and a C----T transition at nucleotide 571, involving the codon CAG encoding Gln106 and producing Gln106----Stop, a mutation described by Emi et al. The functional significance of the two mutations was confirmed by in vitro expression and enzyme activity assays of the mutant LPL. Linkage analysis established that the patient is a compound heterozygote for the two mutations. The Trp86----Arg mutation in exon 3 is the first natural mutation identified outside exons 4-6, which encompass the catalytic triad residues.     

A novel mutation causing mild, atypical fumarylacetoacetase deficiency (Tyrosinemia type I): a case report

Background

A case series of the cardiac magnetic resonance imaging findings in seven adult Alström patients.

Methods

Seven patients from the National Specialist Commissioning Group Centre for Alström Disease, Torbay, England, UK, completed the cardiac magnetic resonance imaging protocol to assess cardiac structure and function in Alström cardiomyopathy.

Results

All patients had some degree of left and right ventricular dysfunction. Patchy mid wall gadolinium delayed enhancement was demonstrated, suggesting an underlying fibrotic process. Some degree of cardiomyopathy was universal. No evidence of myocardial infarction or fatty infiltration was demonstrated, but coronary artery disease cannot be completely excluded. Repeat scanning after 18 months in one subject showed progression of fibrosis and decreased left ventricular function.

Conclusion

Adult Alström cardiomyopathy appears to be a fibrotic process causing impairment of both ventricles. Serial cardiac magnetic resonance scanning has helped clarify the underlying disease progression and responses to treatment. Confirmation of significant mutations in the ALMS1 gene should lead to advice to screen the subject for cardiomyopathy, and metabolic disorders.     

The role of LMNA in adipose: a novel mouse model of lipodystrophy based on the Dunnigan-type familial partial lipodystrophy mutation

We investigated the role of LMNA in adipose tissue by developing a novel mouse model of lipodystrophy. Transgenic mice were generated that express the LMNA mutation that causes familial partial lipodystrophy of the Dunnigan type (FPLD2). The phenotype observed in FPLD-transgenic mice resembles many of the features of human FPLD2, including lack of fat accumulation, insulin resistance, and enlarged, fatty liver. Similar to the human disease, FPLD-transgenic mice appear to develop normally, but after several weeks they are unable to accumulate fat to the same extent as their wild-type littermates. One poorly understood aspect of lipodystrophies is the mechanism of fat loss. To this end, we have examined the effects of the FPLD2 mutation on fat cell function. Contrary to the current literature, which suggests FPLD2 results in a loss of fat, we found that the key mechanism contributing to the lack of fat accumulation involves not a loss, but an apparent inability of the adipose tissue to renew itself. Specifically, preadipocytes are unable to differentiate into mature and fully functional adipocytes. These findings provide insights not only for the treatment of lipodystrophies, but also for the study of adipogenesis, obesity, and insulin resistance.     

Basal wall hypercontraction of Takotsubo cardiomyopathy in a patient who had been diagnosed with dilated cardiomyopathy: a case report

Background

Takotsubo cardiomyopathy is characterized by the basal hypercontractility and apical ballooning of the left ventriculum and T-wave inversion in the electrocardiogram. It has been suggested that Takotsubo cardiomyopathy might underlie the pathogenesis of persistent cardiac dysfunction; however, few reports are present demonstrating the advent of Takotsubo cardiomyopathy in patients with idiopathic cardiomyopathy.

Case presentation

A 64-year-old women was admitted due to dyspnea on effort and lower extremity edema. She had been diagnosed with idiopathic dilated cardiomyopathy 2.5 years before owing to the reduced left ventricular ejection fraction (24%), normal coronary artery, and interstitial fibrosis of the myocardial samples. On admission, her electrocardiogram showed giant negative T wave in II, III, aVF, and precordial leads. Echocardiography showed dyskinesis of the left ventricular apex and hypercontraction of the basal wall, which had not been observed in the previous examinations. Coronary angiography showed normal coronary arteries, and apical ballooning and basal hypercontractility was confirmed by left ventriculography. On day 15 of admission, contraction of apical wall was recovered, and basal hypercontraction was disappeared.

Conclusion

The present case is the first report demonstrating appearance the transient basal wall hypercontraction along with the advent of Takotsubo cardiomyopathy in a patient diagnosed with dilated cardiomyopathy. Whether such findings are indicative of fair prognosis and have the utility of understanding the pathogenesis of dilated cardiomyopathy needs further investigation.

     

A novel transthyretin mutation at position 30 (Leu for Val) associated with familial amyloidotic polyneuropathy.

A novel transthyretin (TTR) mutation associated with familial amyloidotic polyneuropathy was detected in a Japanese patient. Single-strand conformation polymorphism analysis and sequence analysis of polymerase chain reaction (PCR)-amplified exons of the patient's TTR gene revealed a point mutation resulting in a substitution of leucine for valine at position 30. As the mutation creates a Cfr13I site, it was confirmed by PCR and restriction analysis. Our finding indicates the importance of position 30 in TTR-derived amyloid fibril formation.     

From 2R to 3R: evidence for a fish-specific genome duplication (FSGD)

An important mechanism for the evolution of phenotypic complexity, diversity and innovation, and the origin of novel gene functions is the duplication of genes and entire genomes. Recent phylogenomic studies suggest that, during the evolution of vertebrates, the entire genome was duplicated in two rounds (2R) of duplication. Later, approximately 350 mya, in the stem lineage of ray-finned (actinopterygian) fishes, but not in that of the land vertebrates, a third genome duplication occurred-the fish-specific genome duplication (FSGD or 3R), leading, at least initially, to up to eight copies of the ancestral deuterostome genome. Therefore, the sarcopterygian (lobe-finned fishes and tetrapods) genome possessed originally only half as many genes compared to the derived fishes, just like the most-basal and species-poor lineages of extant fishes that diverged from the fish stem lineage before the 3R duplication. Most duplicated genes were secondarily lost, yet some evolved new functions. The genomic complexity of the teleosts might be the reason for their evolutionary success and astounding biological diversity.     

PAX4 mutation (R121W) as a prodiabetic variant in Okinawans

We previously reported that a missense mutation at codon 121 (CGG(Arg) to TGG(Trp), R121W) of PAX4 may be associated with the onset of type 2 diabetes in Japanese. In this study, we determined the frequency of the R121W mutation of PAX4 and characterized the prodiabetic phenotype in a population-based study. Healthy 372 residents participated in annual health check-ups in Nishihara (Okinawa, Japan) and unrelated 193 type 2 diabetic patients from the outpatient clinic of Ryukyu University Hospital were enrolled. Diagnosis of diabetes was based on the 1997 American Diabetes Association criteria. The R121W mutation in PAX4 was genotyped by PCR-RFLP analysis. In healthy residents, R121W mutation was detected in 12 of 372 residents (3.1%). The prevalence of newly diagnosed type 3 diabetes (25% vs. 5%, p=0.004) and HbA(1c) (5.6+/-1.9 vs. 5.1+/-0.7, p=0.026) was higher in the variants than in the wild-types. The odds ratio of diabetes in the R121W variants was 5.98 with 95% confidence interval from 1.50 to 23.9. The R121W mutation was observed in 12 of the 193 type 2 diabetic patients (6.2%). Onset-ages of diabetes were earlier (37+/-10 vs. 47+/-13 years, p=0.010) and the rate of insulin user was two times higher (83% vs. 41%, p=0.005) in the variants. The R121W mutation in PAX4 is a predisposing factor for the development of type 2 diabetes in Okinawans.     

Phenotypic gender differences in subjects with familial partial lipodystrophy (Dunnigan variety) due to a nuclear lamin A/C R482W mutation.

Phenotypic features appeared after puberty in female, but not male subjects with familial partial lipodystrophy (FPLD). We have studied anthropometrical, clinical, and metabolic gender differences in a Spanish family with FPLD resulting from a lamin A/C gene mutation, R482W. Genetic studies were carried out on 14 members of the family. In eleven heterozygous mutation carriers (6 men, 5 women), body composition was evaluated by bioelectric impedance analysis, skin-fold measurements were taken, and lipid profiles were drawn. Moreover, plasma glucose, insulin, and leptin were determined, and insulin resistance and beta cell response were evaluated using HOMA. Ten healthy women and 10 healthy men matched for age and body mass index were used as control group. Body composition was similar in these patients to normal people. However, skin-folds of extremities were thinner in FPLD women compared with those of control subjects, but not in men. The affected women, but not men, showed hypoleptinaemia, insulin resistance, and beta-cell hyperresponse compared with unaffected women. The lipid profile was normal in the young patients, irrespective of sex. Type 2 diabetes mellitus and hypertriglyceridaemia were detected in old and overweight patients only. In conclusion, molecular diagnosis allows us to demonstrate that women with FPLD present both adipose tissue and biochemical abnormalities early in life, and this did not happen in affected men.     

A molecular basis for familial hypertrophic cardiomyopathy: a beta cardiac myosin heavy chain gene missense mutation

A point mutation in exon 13 of the beta cardiac myosin heavy chain (MHC) gene is present in all individuals affected with familial hypertrophic cardiomyopathy (FHC) from a large kindred. This missense mutation converts a highly conserved arginine residue (Arg-403) to a glutamine. Affected individuals from an unrelated family lack this missense mutation, but instead have an alpha/beta cardiac MHC hybrid gene. Identification of two unique mutations within cardiac MHC genes in all individuals with FHC from two unrelated families demonstrates that defects in the cardiac MHC genes can cause this disease. The pathology resulting from a missense mutation at residue 403 further suggests that a critical function of myosin is disrupted by this mutation.     

Superoxide dismutase 1: Identification of a novel mutation in a case of familial amyotrophic lateral sclerosis

Mutation analysis of the superoxide dismutase gene SOD1 in a familial case of amyotrophic lateral sclerosis revealed a T→C transition at codon 151 of exon 5. This mutation results in the substitution of an isoleucine for a threonine. It appears to affect formation of dimers of the protein and is the most C-terminal amino acid change in SOD1 described to date. Received: 5 February 1996 / Revised: 9 February 1996     

Gamma Knife(R) radiosurgery for recurrent intracranial olfactory neuroblastoma (esthesioneuroblastoma): a case report

ABSTRACT: BACKGROUND: We report the use of salvage radiosurgery to manage an aggressive olfactory neuroblastoma(esthesioneuroblastoma) with multiple recurrences and intracranial extension. CASE PRESENTATION: A 43-year-old Caucasian woman presented 11 years ago with progressive nasal blockage andheadaches. A necrotic polyp originating in her left middle meatus and extending to theethmoid air cells and cribriform plate (Kadish stage C) was radically resected via acraniofacial approach. Four years later, a local recurrence extending into her left cavernoussinus was identified and deemed inoperable. She received vincristine, ifosfamide,doxorubicin and etoposide chemotherapy (with minimal benefit) and external beamradiotherapy (60Gy in 30 fractions) to her skull base. Two years later, tumour extension inher left neck was treated with radical radiotherapy. She developed visual disturbances in herleft eye, which progressed to blindness in the next two years. Having exhaustedchemoradiotherapy, the left cavernous sinus esthesioneuroblastoma was treated with GammaKnife? radiosurgery 2 years ago (20Gy at 50% isodose, tumour volume 7.5cm3). At oneyear, there was dramatic reduction in the tumour and no new symptoms; however, there werenew tumour foci (in her left frontal lobe and above her right orbital apex). These were againtreated with radiosurgery (20Gy at 50% isodose, total tumour volume 0.67cm3). Repeatimaging at six months showed no further disease progression. CONCLUSION: Whilst rare, olfactory neuroblastoma (esthesioneuroblastoma) can present managementchallenges and Gamma Knife(R) radiosurgery may prove a useful strategy in controllingintracranial spread.     

A missense mutation (R565W) in cirhin (FLJ14728) in North American Indian childhood cirrhosis

North American Indian childhood cirrhosis (CIRH1A, or NAIC), a severe autosomal recessive intrahepatic cholestasis described in Ojibway-Cree children from northwestern Quebec, is one of several familial cholestases with unknown molecular etiology. It typically presents with transient neonatal jaundice, in a child who is otherwise healthy, and progresses to biliary cirrhosis and portal hypertension. Clinical and physiological investigations have not revealed the underlying cause of the disease. Currently, liver transplantation is the only effective therapy for patients with advanced disease. We previously identified the NAIC locus by homozygosity mapping to chromosome 16q22. Here we report that an exon 15 mutation in gene FLJ14728 (alias Cirhin) causes NAIC: c.1741C-->T in GenBank cDNA sequence NM_032830, found in all NAIC chromosomes, changes the conserved arginine 565 codon to a tryptophan, altering the predicted secondary structure of the protein. Cirhin is preferentially expressed in embryonic liver, is predicted to localize to mitochondria, and contains WD repeats, which are structural motifs frequently associated with molecular scaffolds.