Virginia V. Michels

The Frequency of Familial Dilated Cardiomyopathy in a Series of Patients with Idiopathic Dilated Cardiomyopathy

BACKGROUND Dilated cardiomyopathy is characterized by an increase in ventricular size and impairment of ventricular function. Most cases are believed to be sporadic, and familial dilated cardiomyopathy is usually considered to be a rare and distinct disorder. We studied the proportion of cases of idiopathic dilated cardiomyopathy that were familial in a large sequential series of patients whose first-degree relatives were investigated regardless of whether these relatives had cardiac symptoms. METHODS We studied relatives of 59 index patients with idiopathic dilated cardiomyopathy of obtaining a family history and performing a physical examination, electrocardiography, and two-dimensional, M-mode, and Doppler echocardiography. A total of 315 relatives were examined. RESULTS Eighteen relatives from 12 families were shown to have dilated cardiomyopathy. Thus, 12 of the 59 index patients (20.3 percent) had familial disease. There was no difference in age, sex, severity of disease, exposure to selected environmental factors, or electrocardiographic or echocardiographic features between the index patients with familial disease and those with nonfamilial disease. A noteworthy finding was that 22 of 240 healthy relatives (9.2 percent) with normal ejection fractions had increased left ventricular diameters during systole or diastole (or both), as compared with 2 of 112 healthy control subjects (1.8 percent) who were studied separately. CONCLUSIONS Dilated cardiomyopathy was found to be familial in at least one in five of the patients in this study, a considerably higher percentage than in previous reports. This finding has important implications for family screening and provides direction for further investigation into the causes and natural history of dilated cardiomyopathy.

Prevalence and etiology of idiopathic dilated cardiomyopathy (summary of a National Heart, Lung, and Blood Institute Workshop)

Idiopathic dilated cardiomyopathy (IDC) is the primary indication for cardiac transplantation, with associated costs of approximately

Neurovascular manifestations of heritable connective tissue disorders. A review.

177 million per year. Recognizing the economic implications of IDC, the increasing incidence, and the limited information on pathogenesis and prognosis, the National Heart, Lung, and Blood Institute convened a workshop on the Prevalence and Etiology of Idiopathic Dilated Cardiomyopathy on June 13 to 14, 1991. The difficulties of studying the disease were reviewed, including its relatively low prevalence, its potentially pluricausal nature, and the fact that it is often a diagnosis of exclusion. Still, it presents significant challenges to the cardiovascular scientific community, since the mechanism of myocardial damage and related etiologic and prognostic factors are virtually unknown. The development of more reliable measures of immune-mediated damage and noninvasive measures of impaired cardiac function present new research opportunities in this disorder. Standardized diagnostic criteria for use in observational and interventional trials were developed, and priorities for future research were proposed. Population-based registries and nested case-control studies, where feasible, are appropriate study designs for tracking incidence and prevalence, and for identifying risk factors, respectively. Interventional studies should focus on secondary prevention, through modifying immune-mediated damage in clinically evident dilated cardiomyopathy, and through prevention of sudden death in patients with the disorder. Primary prevention trials must await the identification of modifiable risk factors and of appropriate and effective interventions.

Mutations in Ribonucleic Acid Binding Protein Gene Cause Familial Dilated Cardiomyopathy

Background Heritable disorders of connective tissue are recognized in a small minority of patients with neurovascular diseases. In this report, we review the neurovascular manifestations of four heritable connective tissue disorders: Ehlers‐Danlos syndrome, Marfans syndrome, osteogenesis imperfecta, and pseudoxanthoma elasticum, as well as two other systemic disorders with potential vascular manifestations: neurofibromatosis and polycystic kidney disease. Summary of Review Typical neurovascular complications of Ehlers‐Danlos syndrome are carotid‐cavernous fistulae, intracranial aneurysms, and cervical artery dissections. Arterial dissections and intracranial aneurysms cause the majority of neurovascular symptoms in Marfans syndrome. Neurovascular disease is uncommon in osteogenesis imperfecta, although carotid‐cavernous fistulae and vertebral artery dissections have been reported. Neurovascular disease in pseudoxanthoma elasticum is characterized by intracranial aneurysms and cerebral ischemia caused by premature arterial occlusive disease. Intracranial occlusive arterial disease is the most common neurovascular manifestation of neurofibromatosis, followed by cervical arteriovenous fistulae and aneurysms and intracranial aneurysms. Intracranial aneurysms are the hallmark of polycystic kidney disease. Conclusions Recognition of an underlying generalized connective tissue disorder may be of considerable importance, although marked phenotypic heterogeneity often complicates the diagnosis of these disorders. Conversely, the association of certain neurovascular anomalies with generalized connective tissue disorders and recognition of their basic molecular defect may offer clues to the etiology and pathogenesis of these neurovascular diseases in general. (Stroke. 1994;25:889‐903.)

On the inheritance of intracranial aneurysms.

OBJECTIVES We sought to identify a novel gene for dilated cardiomyopathy (DCM). BACKGROUND DCM is a heritable, genetically heterogeneous disorder that remains idiopathic in the majority of patients. Familial cases provide an opportunity to discover unsuspected molecular bases of DCM, enabling pre-clinical risk detection. METHODS Two large families with autosomal-dominant DCM were studied. Genome-wide linkage analysis was used to identify a disease locus, followed by fine mapping and positional candidate gene sequencing. Mutation scanning was then performed in 278 unrelated subjects with idiopathic DCM, prospectively identified at the Mayo Clinic. RESULTS Overlapping loci for DCM were independently mapped to chromosome 10q25-q26. Deoxyribonucleic acid sequencing of affected individuals in each family revealed distinct heterozygous missense mutations in exon 9 of RBM20, encoding ribonucleic acid (RNA) binding motif protein 20. Comprehensive coding sequence analyses identified missense mutations clustered within this same exon in 6 additional DCM families. Mutations segregated with DCM (peak composite logarithm of the odds score >11.49), were absent in 480 control samples, and altered residues within a highly conserved arginine/serine (RS)-rich region. Expression of RBM20 messenger RNA was confirmed in human heart tissue. CONCLUSIONS Our findings establish RBM20 as a DCM gene and reveal a mutation hotspot in the RS domain. RBM20 is preferentially expressed in the heart and encodes motifs prototypical of spliceosome proteins that regulate alternative pre-messenger RNA splicing, thus implicating a functionally distinct gene in human cardiomyopathy. RBM20 mutations are associated with young age at diagnosis, end-stage heart failure, and high mortality.

Distribution of sodium-lithium countertransport and blood pressure in Caucasians five to eighty-nine years of age.

The familial occurrence of intracranial aneurysms suggests the presence of a genetically determined underlying arteriopathy. The pattern of inheritance in these families usually is not known. Methods A family with seven members with intracranial aneurysms is described and, from the literature before 1994, a total of 238 families with 560 affected members (56% female and 44% male) with intracranial aneurysms not associated with a known heritable disease are reviewed. A segregation analysis was performed on 73 of these families. Results Two members were affected in the great majority of families (79%); five or more members were reported in only eight families (3%). The most common affected kinship was among siblings. Angiographic screening in 12 families detected an intracranial aneurysm in 29% of 51 asymptomatic relatives. Segregation analysis revealed several patterns of inheritance that were consistent with the compiled pedigrees, but no single mendelian model was the overall best fitting, suggesting that genetic heterogeneity may be important. Twenty-two percent of siblings of male probands had an intracranial aneurysm compared with 9% of siblings of female probands (P=.003). Conclusions Genetic heterogeneity may be important in the genetics of intracranial aneurysms. In families with intracranial aneurysms, siblings of an affected male proband may be at a higher risk of developing an aneurysm than siblings of an affected female proband. Screening for intracranial aneurysms in asymptomatic relatives should be considered in families with two or more affected members. In most families, the nature of the underlying arteriopathy remains obscure.

Heritable connective tissue disorders in cervical artery dissections: A prospective study

Case-control studies suggest that increased erythrocyte sodium-lithium countertransport may predict increased susceptibility to the development of essential hypertension. To characterize interindividual variation in sodium-lithium countertransport and its relation to blood pressure levels in the general population, we studied 1,475 Caucasians between 5 and 89 years of age (711 males and 764 females) ascertained through 266 households with children in the schools of Rochester, Minnesota. Individuals who were taking antihypertensive agents or combinations of estrogen and progesterone were not included in the sample. A third-order polynomial regression on age accounted for only a small fraction of variability in sodium-lithium countertransport (2.8% in males, p less than 0.001; 2.1% in females, p less than 0.01), whereas a fourth-order regression on age accounted for a large proportion of variability in systolic blood pressure (45.7% in males, p less than 0.001; 52.5% in females, p less than 0.001) and diastolic blood pressure (39.8% in males, p less than 0.001; 33.0% in females, p less than 0.001). Mean sodium-lithium countertransport was higher in males than females at all ages; but the rank order of male and female means for systolic and diastolic blood pressure was age dependent. Positively skewed distributions for age-, height-, and weight-adjusted sodium-lithium countertransport in male and female cohorts between 5-19.9, 20-49.9, and 50-89.9 years of age were explained significantly better by postulating a mixture of two partially overlapping sodium-lithium countertransport distributions rather than a single normal distribution (p less than 0.01). Among men in the 20-49.9-year-old cohort, adjusted sodium-lithium countertransport values in the upper distribution were associated with higher systolic and diastolic blood pressure (mean +/- SD) than values in the lower distribution (for systolic blood pressure: 115 +/- 11 vs. 111 +/- 11 mm Hg, p less than 0.07; for diastolic blood pressure: 71.2 +/- 8.0 vs. 68.4 +/- 8.6 mm Hg, p less than 0.08). Among females in the 50-89.9-year-old cohort, adjusted sodium-lithium countertransport values in the upper distribution were associated with significantly greater diastolic blood pressure than values in the lower distribution (77 +/- 10 vs. 70 +/- 9 mm Hg, p less than 0.03).(ABSTRACT TRUNCATED AT 400 WORDS)

Von Hippel–Lindau Disease

We prospectively evaluated 15 consecutive patients with spontaneous cervical artery dissections. Three patients (20%) had a heritable connective tissue disorder, each with a unique phenotype. None of these patients met the criteria of any of the named syndromes, and collagen and fibrillin analyses were normal. Heritable connective tissue disorders are common among patients with spontaneous cervical artery dissections, but, despite intensive investigations, the type of disorder usually cannot be identified. The underlying arteriopathy in cervical artery dissections is likely to be heterogenous.

Intracranial aneurysms in Marfan's syndrome: an autopsy study.

An autosomal dominant tumor predisposition syndrome, von Hippel-Lindau disease (VHL) is characterized by the presence of benign and malignant tumors. Hallmark lesions include retinal angiomas, hemangioblastomas of the cerebellum and spinal cord, and renal cell carcinomas. Affected persons may also have angiomatous or cystic lesions of the kidneys, pancreas, and epididymis, as well as adrenal pheochromocytomas. In this article, we discuss the clinical features and diagnostic criteria for this clinically underdiagnosed condition. An update on recent findings regarding the molecular genetics of VHL is provided, including a discussion of the evolving understanding of genotype-phenotype correlations. Understanding the molecular and functional aspects of this condition will lead to the development of strategies for the management and treatment of inherited and sporadic VHL-associated tumors.

Screening for hemochromatosis: A cost-effectiveness study based on 12,258 patients

OBJECTIVE Marfans syndrome is a heritable connective tissue disorder that has been associated with intracranial aneurysms. However, the prevalence of intracranial aneurysms in Marfans syndrome is unknown and pathological studies of affected vessels have not been reported. We therefore examined the neuropathological findings in a group of patients with Marfans syndrome. METHODS We identified all patients with Marfans syndrome in whom postmortem examination had been performed at the Mayo Clinic between 1969 and 1993. RESULTS Autopsy included examination of the brain in seven patients with Marfans syndrome (five men and two women with a mean age of 28 yr). Each of two patients had one or more intracranial aneurysms. The first patient, a 32-year-old man who died as a result of aortic dissection, was observed to have an incidental saccular supraclinoid carotid artery aneurysm (7 mm). Microscopic examination of the remainder of the cerebral arteries revealed duplication and fragmentation of the internal elastic lamina. The second patient, a 20-year-old man who died as a result of a subarachnoid hemorrhage, had ruptured saccular supraclinoid carotid artery (3 mm) and anterior cerebral artery (20 mm) aneurysms as well as unruptured fusiform middle cerebral artery (18 mm) and posterior cerebral artery (13 mm) aneurysms. Microscopic examination of the cerebral arteries revealed widespread changes consisting of intimal proliferation, medial degeneration, and fragmentation of the internal elastic lamina. CONCLUSION These findings confirm an association between Marfans syndrome and intracranial aneurysms. Microscopic involvement of cerebral arteries in Marfans syndrome may be variable, even among those with intracranial aneurysms.