A trinucleotide deletion in the transthyretin gene (delta V 122) in a kindred with familial amyloidotic polyneuropathy

A 63-year-old white man of Ecuadorian origin had a subarachnoid hemorrhage at age 57 followed by numbness and paresthesia in his lower extremities. He subsequently developed sexual impotence, alternating constipation and diarrhea, urinary frequency, and difficulty in walking. Rectal biopsy revealed amyloid deposits immunohistochemically reactive with antitransthyretin antisera. Direct DNA sequencing of the transthyretin gene of the patient showed a trinucleotide deletion in exon 4. This deletion resulted in the loss of one of two valines at position 121 or 122. DNA analysis on 11 family members at risk revealed four mutant gene carriers. Plasma transthyretin levels in the mutant gene carriers measured by nephelometry were very low. Peptide sequence analysis revealed that most of plasma transthyretin was normal with only a small amount of variant protein. This is the first report of a DNA deletion in the transthyretin gene. We speculate that the loss of valine in the carboxyl terminal region of the transthyretin monomer alters stability of the tetrameric protein, which leads to rapid clearance from the plasma and amyloid deposition in the tissue.     

Fatal familial insomnia: genetic, neuropathologic, and biochemical study of a patient from a new Italian kindred

Fatal familial insomnia (FFI) is an inherited prion disease linked to a mutation at codon 178 of the PRNP gene that results in aspartic acid to asparagine substitution, in coupling phase with methionine at position 129. The disease is characterized clinically by insomnia with disturbances of the autonomic, endocrine, and motor systems and neuropathologically by selective degeneration of the thalamus. Phenotypic variability is well known and has been linked to homozygosity or heterozygosity at PRNP codon 129. We report the clinical, neuropathologic, and biochemical findings and genomic analysis of a patient with FFI from a new Italian kindred. Although homozygous for methionine at codon 129, this patient showed some clinical and pathologic features most commonly found in heterozygotes.     

Obstructive and non-obstructive hypertrophic cardiomyopathy: clinical, electrocardiographic, and echocardiographic differences

AIM: The purpose of the study was to analyse echocardiographic, electrocardiographic and clinical variables in patients with hypertrophic cardiomyopathy, as well as to compare the possible differences between the non-obstructive (NOHCM) and the obstructive form (OHCM). METHOD: 44 consecutive patients were studied and diagnosed with hypertrophic cardiomyopathy (NOHCM 26 and OHCM 18). The following variables were analysed: 1) echocardiographic: right ventricle (RV), interventricular septum (IVS), posterior wall (pW), telediastolic and telesystolic diameter of the left ventricle (TDD-LV and TSD-LV), size of the left atrium (LA), systolic anterior motion of the mitral valve (SAM), mitral insufficiency and direction of the jet (MI and MIpW), mitral anular calcium (MAC), filling pattern (A > E); 2) electrocardiographic: repolarization disorders (RD), left ventricular hypertrophy (LVH), negative "T" waves in the precordial leads (T-), pathological "q" waves, super or ventricular arrhythmias (SA or VA), short PR, right or left bundle branch block (RBBB and LBBB), and 3) clinical: presence of dyspnea, angina, syncope, palpitations and response to treatment with beta-blockers (B-b) or Calcium-antagonists (C-A). RESULTS: There were no differences in age or sex between the obstructive and non-obstructive groups: 1) echocardiographic differences: there were none in RV, pW, TDD-LV, LA nor A > E wave. Significant differences were found (p < 0.05) in the rest of the variables; IVS (16 +/- 3 mm in NOHCM vs 22 +/- 5 mm in OHCM), TSD-LV (26 +/- 5 mm in NOHCM vs 22 +/- 6 mm in OHCM), SAM (38% in NOHCM vs 89% in OHCM), MI (19% in NOHCM vs 78% in OHCM), MIpW (20% in NOHCM vs 79% in OHCM), MAC (15% in NOHCM vs 44% in OHCM); 2) electrocardiographic differences: there were none in the presence of RD, pathological "q", VA, short PR, RBBB nor LBBB. The presence of "T" negatives was on the limit of significance in the precordial leads (31% in NOHCM vs 11% in OHCM; p = 0.09). Differences were found in the rest of the variables; LVH (58% in NOHCM vs 83% in OHCM), SA (50% in NOHCM vs 17% in OHCM); 3) clinical differences: there were none in the presence of dyspnea, angina, syncope or palpitations. Differences were found in the improvement with treatment; B-b (60% in NOHCM vs 57% in OHCM), C-A (100% in NOHCM vs 100% in OHCM). CONCLUSIONS: 1) in our patients, the most frequent cardiomyopathy is the non-obstructive one, with no predominance of age or sex; 2) in OHCM, IVS is much wider, with smaller TSD-LV, there is a greater incidence of MI, generally directed towards the posterior wall of the left atrium, and a larger tendency to calcify the mitral annulus; 3) the most frequent electrocardiographic abnormality is the alteration of repolarization. NOHCM has a greater incidence of SA and a lower degree of LVH with more prevalence of negative "T" waves in the precordial leads; 4) there are no clinical parameters differentiating the two groups, although the sustained improvement obtained with treatment is more likely to be produced by the calcium-antagonists than by beta-blockers in both types of cardiomyopathy.     

A late onset familial amyloidotic polyneuropathy (FAP) with a novel variant transthyretin characterized by a basic-for-acidic amino acid substitution (Glu61-->Lys)

A 64-year-old man has suffered from intractable diarrhea since January 1990. He noticed numbness and weakness in the distal portion of four extremities in the following several months. His symptoms were gradually progressive. In June 1992, neurological examination revealed mild muscular atrophy and weakness in the proximal and distal portions of four extremities. There were paresthesia and severe impairment of superficial sensations in the lower limbs, lower half of the trunk and upper limbs. All deep tendon reflexes were reduced or absent. Autonomic dysfunctions such as orthostatic hypotension, impotence and diarrhea were evident. On sural nerve biopsy, myelinated fibers showing axonal degeneration were predominantly seen, and densities of both myelinated and unmyelinated fibers were markedly decreased. No amyloid deposits were found in the endoneurium. Amyloid deposition was identified in the gastric mucosa by Congo red staining and immunostaining with anti-transthyretin (TTR) antibody. Edman degradation showed one amino acid substitution of Lys for Glu at position 61 in the TTR-peptides from the serum. Direct DNA sequencing revealed a new point mutation in the 61st codon of TTR gene. The same point mutation of TTR gene was identified in the DNAs from his 67-year-old brother and 63-year-old sister and one of the paternal cousins, a 64-year-old woman, although their clinical symptoms and signs were negative. Clinical features such as late onset of the symptoms and signs and presence of carriers in their sixties in this family are unique and atypical as compared with those of more frequent Val30-->Met FAP families. A variant TTR, characterized by a Glu61-->Lys substitution (a basic-for-acidic amino acid substitution) found in this family, has not been reported in the literature. In the case of the examination of the patients with autonomic and sensory symptoms and signs of unknown etiology, amyloidotic polyneuropathies, including FAP even in the absence of the family history, should be differentiated. When FAP is highly suspected, the combination of family study and DNA analysis of a possible variant TTR is indispensable for the establishment of the diagnosis.     

Reduced penetrance, variable expressivity, and genetic heterogeneity of familial atrial septal defects

BACKGROUND: Secundum atrial septal defect (ASD) is a common congenital heart malformation that occurs as an isolated anomaly in 10% of individuals with congenital heart disease. Although some embryological pathways have been elucidated, the molecular etiologies of ASD are not fully understood. Most cases of ASD are isolated, but some individuals with ASD have a family history of this defect or other congenital heart malformations. METHODS AND RESULTS: Clinical evaluation of three families identified individuals with ASD in multiple generations. ASD was transmitted as an autosomal dominant trait in each family. ASD was the most common anomaly, but other heart defects occurred alone or in association with ASD in individuals from each kindred. Genome-wide linkage studies in one kindred localized a familial ASD disease gene to chromosome 5p (multipoint LOD score=3.6, theta=0.0). Assessment of 20 family members with the disease haplotype revealed that 9 had ASD, 8 were clinically unaffected, and 3 had other cardiac defects (aortic stenosis, atrial septal aneurysm, and persistent left superior vena cava). Familial ASD did not map to chromosome 5p in two other families. CONCLUSIONS: Familial ASD is a genetically heterogeneous disorder; one disease gene maps to chromosome 5p. Recognition of the heritable basis of familial ASD is complicated by low disease penetrance and variable expressivity. Identification of ASD or other congenital heart defects in more than one family member should prompt clinical evaluation of all relatives.     

Clinical and genetic analysis of a pedigree of a thirty-six-year-old familial Alzheimer''s disease patient

Distribution of apolipoprotein(apo) E4 and E3 in lipoproteins of serum with apoE4/E3 phenotype was analyzed. ApoE was eluted in two major peaks by gel chromatography; peak 1 and 2 corresponding to very- and intermediate-low density lipoprotein (VLDL + IDL) and high density lipoprotein2 (HDL2), respectively. ApoE in peak 1 (VLDL + IDL) consisted of monomers of 34 kDa, complexes with a high molecular weight (apoEs) of 100 kDa and with a small amount of apoE-AII complexes weighing 43 kDa. In contrast, apoE in peak 2 (HDL2) was composed mainly of apoE-AII complexes and apoEs complexes, and a small amount of monomers. Both apoE3 and E4 isoforms were detected in these peaks; E4 was more predominant in peak 1 while E3 was more predominant in peak 2. These findings suggest that different distributions of apoE3 and E4 in lipoprotein particles.     

Autosomal dominant striatonigral degeneration. A clinical, pathologic, and biochemical study of a new genetic disorder

An autosomal dominant striatonigral degeneration is present in a family of Portuguese ancestry numbering in excess of 329 persons in eight generations. The illness begins in the second, third, or fourth decade, and progresses for about 15 years with parkinsonian rigidity, spasticity, spastic dysarthria, and abnormalities of eye movement. Neuropathologic findings are severe neuronal loss and astrocytic gliosis in the corpus striatum and substantia nigra, with a moderate neuronal loss in the dentate nucleus of the cerebellum and nucleus ruber of the midbrain. This is a new genetic entity, distinct from other autosomal dominant neurologic disorders such as nigrospinodentatal degeneration, olivopontocerebellar degeneration, dystonia musculorum deformans, Machado's disease, and Huntington's disease.     

Structural, functional, and genetic characterization of Gastrophilus hemoglobin

Hemoglobin of Gastrophilus intestinalis (Insecta, Diptera), was purified and characterized. At least two isoforms have been identified by isoelectrofocusing, mass spectrometry, and genomic Southern blotting. Functional studies show a high oxygen affinity due to a low ligand dissociation rate (koff = 2.4 s-1) and a relatively high autoxidation rate (t1/2 = 1.6/h). The globins were separated under denaturing conditions, and the sequence of Hb1 (Mr = 17,965 +/- 2) was determined at the protein and DNA level. The open reading frame codes for a polypeptide of 150 amino acids. Although the globin is distantly related to globins from other species, it has a low penalty score against globin templates. Freshly isolated hemoglobin was crystallized from polyethylene glycol. Crystals contain two hemoglobin molecules per asymmetric unit. Solution of the three-dimensional structure by molecular replacement could not be achieved, possibly due to the presence of three protein isoforms in the crystals. In order to determine its three-dimensional structure, G. intestinalis Hb1 was overexpressed in Escherichia coli, resulting in a fully functional molecule as confirmed by ligand binding affinity. The globin gene contains two introns at positions D7.0 and G7.0. The D7.0 intron is unprecedented, suggesting that globin gene evolution is much more complex than originally thought.     

Comparison of clinical and morphologic cardiac findings in patients having cardiac transplantation for ischemic cardiomyopathy, idiopathic dilated cardiomyopathy, and dilated hypertrophic cardiomyopathy

This article compares intergroup and intragroup clinical and morphologic findings in patients with ischemic cardiomyopathy (IC), idiopathic dilated cardiomyopathy (IDC), and dilated hypertrophic cardiomyopathy (HC) undergoing cardiac transplantation (CT). Few previous publications have described findings in native hearts explanted at the time of CT. The explanted heart in 92 patients having CT was examined in uniform manner with particular attention to the sizes of the ventricular cavities and the presence of and extent of ventricular scarring. Of the 92 hearts examined, 47 had IC, 35 had IDC, and 10 had dilated HC. Although considerable degrees of intragroup variation occurred, the mean degree of left ventricular dilatation was similar among the patients with IC, IDC, and dilated HC. All patients with IC had left ventricular free wall scarring more extensive than that involving the ventricular septum, but the intragroup variation in the amounts of scarring was considerable. Nine of the 10 patients with dilated HC also had ventricular wall scarring, but it was more extensive in the ventricular septum than in the left ventricular free wall and involvement of the right ventricular wall also was present. Eight (23%) of the 35 IDC patients also had grossly visible ventricular scars but they were small and only 1 of the 8 had coronary narrowing and that was not in the distribution of the scarring. Narrowing of 1 or more epicardial coronary arteries >75% in cross-sectional area by plaque was present in all 47 IC patients, in 8 of the 35 IDC patients (7 had no ventricular scars), and in none of the 10 dilated HC patients. Coronary angiography was the major clinical tool allowing separation of the IC, IDC, and HC patients. Coronary angiography did not detect narrowing in any of the 8 patients with IDC who were found to have coronary narrowing on anatomic study. Thus, among patients with IC, IDC, and dilated HC having CT, distinctive anatomic features allow separation of patients with IC, IDC, and dilated HC, but within each group considerable variation in left ventricular cavity size and extent of ventricular scarring occurs.     

Congestive heart failure in patients with valvular aortic stenosis. A clinical and echocardiographic Doppler study

The aim of this study was to evaluate echographically anatomic and functional features of the left ventricle in adult patients with valvular aortic stenosis according to the presence or absence of congestive heart failure and the level of ventricular performance. Fifty-six adult patients with moderate-to-severe aortic stenosis underwent echocardiographic Doppler examination in order to evaluate left ventricular mass and dimensions, systolic function and filling dynamics. Twenty-seven patients had no heart failure and were symptomatic for angina (5), syncope (4) or were symptom-free (group I); the other 29 had heart failure (group II): 16 with normal left ventricular systolic performance (fractional shortening > 25%, group IIa) and 13 with systolic dysfunction (fractional shortening < or = 25%, group IIb). Despite a similar left ventricular mass, compared to group IIa, group IIb showed a significant left ventricular dilatation (end-diastolic diameter: 61 +/- 6.5 vs. 45.5 +/- 6.1 mm, p < 0.001) and mild or no increase in wall thickness (11.5 +/- 1.6 vs. 14.9 +/- 2 mm, p < 0.001). Indices of left ventricular filling on Doppler transmitral flow were also significantly different between the two groups, with a higher early-to-late filling ratio and a shorter deceleration time of early filling in group IIb (2.8 +/- 1.9 vs. 1.2 +/- 0.85, p < 0.01, and 122 +/- 66 vs. 190 +/- 87 ms, p < 0.05, respectively), both indirectly indicating higher left atrial pressure. Finally, heart failure was generally more severe in group IIb patients. In some patients with aortic stenosis, symptoms of heart failure may be present despite a normal left ventricular systolic function and seem to depend on abnormalities of diastolic function. The presence of systolic or isolated diastolic dysfunction appears to be related to a different geometric adaptation of the left ventricle to chronic pressure overload.     

Linkage of familial dilated cardiomyopathy with conduction defect and muscular dystrophy to chromosome 6q23

Inherited cardiomyopathies may arise from mutations in genes that are normally expressed in both heart and skeletal muscle and therefore may be accompanied by skeletal muscle weakness. Phenotypically, patients with familial dilated cardiomyopathy (FDC) show enlargement of all four chambers of the heart and develop symptoms of congestive heart failure. Inherited cardiomyopathies may also be accompanied by cardiac conduction-system defects that affect the atrioventricular node, resulting in bradycardia. Several different chromosomal regions have been linked with the development of autosomal dominant FDC, but the gene defects in these disorders remain unknown. We now characterize an autosomal dominant disorder involving dilated cardiomyopathy, cardiac conduction-system disease, and adult-onset limb-girdle muscular dystrophy (FDC, conduction disease, and myopathy [FDC-CDM]). Genetic linkage was used to exclude regions of the genome known to be linked to dilated cardiomyopathy and muscular dystrophy phenotypes and to confirm genetic heterogeneity of these disorders. A genomewide scan identified a region on the long arm of chromosome 6 that is significantly associated with the presence of myopathy (D6S262; maximum LOD score [Z(max)] 4.99 at maximum recombination fraction [theta(max)] .00), identifying FDC-CDM as a genetically distinct disease. Haplotype analysis refined the interval containing the genetic defect, to a 3-cM interval between D6S1705 and D6S1656. This haplotype analysis excludes a number of striated muscle-expressed genes present in this region, including laminin alpha2, laminin alpha4, triadin, and phospholamban.     

Utility of an integrated clinical, echocardiographic, and venous ultrasonographic approach for triage of patients with suspected pulmonary embolism

The potential role of ultrasound techniques in diagnosing acute pulmonary embolism (PE) has been investigated in severe cases with hemodynamic compromise, but is still unclear for the whole clinical spectrum of patients with suspected PE. The aim of this study was to assess the utility of an integrated bedside evaluation for PE based on the combination of a clinical score, 2-dimensional echocardiography, and color venous duplex scanning. A group of 117 consecutive patients with suspected PE was assessed using a clinical likelihood score, echocardiography, and venous duplex scanning in order to obtain a preliminary diagnosis of PE, which was subsequently compared with the final diagnosis obtained by lung perfusion scintigraphy and angiography. A preliminary diagnosis of PE was made in 70 patients; a final diagnosis of PE was made in 63 patients, of which 56 had and 7 did not have a preliminary diagnosis of PE. The preliminary diagnosis therefore showed 89% sensitivity and 74% specificity, with a total accuracy of 82%. In patients with massive PE, sensitivity and negative predictive values of the preliminary diagnosis were 97% and 98%, respectively. Echocardiography was poorly sensitive (51%) but highly specific (87%) for PE. Thus, the integration of clinical likelihood, echocardiography, and venous duplex scanning provides a practical approach to patients with suspected PE, allows the rapid implementation of appropriate management strategies, and may reduce or postpone the need for further instrumental evaluation of more limited access.     

Atrial arrhythmias in adults after repair of tetralogy of Fallot. Correlations with clinical, exercise, and echocardiographic findings

BACKGROUND: The long-term success of intracardiac repair of tetralogy of Fallot is hampered by the occurrence of arrhythmias. Numerous studies have stressed the potential role of ventricular arrhythmias. However, the importance of other arrhythmias in the morbidity of these patients appears to be underestimated. Furthermore, most follow-up studies have been limited to children or adolescents, whereas many patients have reached adulthood after earlier repair of tetralogy of Fallot. The aim of the present study was to determine the incidence of atrial fibrillation, atrial flutter, and other supraventricular arrhythmias in adult patients after intracardiac repair for tetralogy of Fallot and their correlation with surgical and clinical findings. METHODS AND RESULTS: The study group consisted of 53 consecutive patients referred to the Thoraxcenter adult congenital heart disease clinic. They underwent repair at a mean age of 9.1 years (range, 0.7 to 55 years). The median age at the time of study was 23.2 years (range, 15 to 57 years; mean age, 26.6 years), and the mean duration of follow-up of 17.5 years (range, 1.4 to 32 years) after surgery. Records were reviewed extensively for evidence of arrhythmias. The follow-up study included routine 12-lead ECG, 24-hour continuous ambulatory monitoring, and echocardiography, and 46 patients underwent exercise testing. Sinus node dysfunction was recorded in 19 patients (36%), of whom 4 required a permanent pacemaker. Atrial fibrillation or flutter was found in 12 patients, and other supraventricular tachycardias were found in 6. The former were more frequently of older age at follow-up. Antiarrhythmic therapy and cardioversion were typically directed at control of atrial (and not ventricular) tachyarrhythmias. Ten patients (19%) showed nonsustained ventricular tachycardia; they were older at initial surgery and older at follow-up and had more intracardiac repairs and longer cardiopulmonary bypass times. CONCLUSIONS: Despite an emphasis on ventricular ectopy in past series, the main sources of morbidity in adult patients after surgical correction of tetralogy of Fallot emanated from atrial arrhythmias, which were present in one third of the patients.     

Genetic analysis of a kindred with X-linked mental handicap and retinitis pigmentosa

A kindred is described in which X-linked nonspecific mental handicap segregates together with retinitis pigmentosa. Carrier females are mentally normal but may show signs of the X-linked retinitis pigmentosa carrier state and become symptomatic in their later years. Analysis of polymorphic DNA markers at nine loci on the short arm of the X chromosome shows that no crossing-over occurs between the disease and Xp11 markers DXS255, TIMP, DXS426, MAOA, and DXS228. The 90% confidence limits show that the locus is in the Xp21-q21 region. Haplotype analysis is consistent with the causal gene being located proximal to the Xp21 loci DXS538 and 5'-dystrophin on the short arm of the X chromosome. The posterior probability of linkage to the RP2 region of the X chromosome short arm (Xp11.4-p11.23) is .727, suggesting the possibility of a contiguous-gene-deletion syndrome. No cytogenetic abnormality has been identified.     

Cloning and functional characterization of the 5''-flanking region of human methionine adenosyltransferase 2A gene

Electron microscopy of dimeric and trimeric single chain antibody Fv fragments (scFvs) complexed with anti-idiotype Fab fragments was used to reveal the orientation of antigen binding sites. This is the first structural analysis that discloses the multivalent binding orientation of scFv trimers (triabodies). Three different scFv molecules were used for the imaging analysis; NC10 scFv-5 and scFv-0, with five- and zero-residue linkers respectively between the VH and VL domains, were complexed with 3-2G12 anti-idiotype Fab fragments and 11-1G10 scFv-0 was complexed with NC41 anti-idiotype Fab fragments. The scFv-5 molecules formed bivalent dimers (diabodies) and the zero-linker scFv-0 molecules formed trivalent trimers (triabodies). The images of the NC10 diabody-Fab complex appear as boomerangs, not as a linear molecule, with a variable angle between the two Fab arms and the triabody-Fab complexes appear as tripods.