Mitral valve dysfunction in the Marfan syndrome. Clinical and echocardiographic study of prevalence and natural history

Current insights in diagnosis and management of the cardiovascular complications of Marfan's syndrome

Marfan's syndrome is an inherited disorder of connective tissue, caused by mutations in the fibrillin-1 gene located on chromosome 15. Diagnosis is still based on a combination of major and minor clinical features. Prognosis is mainly determined by the cardiovascular complications. Advances in surgical and medical treatment for these complications have dramatically improved the prognosis of the syndrome.

[Marfan syndrome and valvular disease]

Marfan syndrome is a hereditary disease of the connective tissue with increased mortality mostly due to changes of the cardiovascular system. We describe our experience with the surgical treatment of 243 patients with Marfan syndrome and cardiovascular complications. We report the results of treatment of annulo-aortal ectasia using the classical surgical methods of Bentall DeBono and Cabrol and the method for preservation of the native aortic valve and concomitant surgery of the mitral valve. Reconstruction or replacement of the mitral valve is mainly based on the classical indications. Preservation of the native aortic valve and reconstruction of the mitral valve in patients with Marfan syndrome is possible but the long-term results are still unknown.

Natural history of cardiovascular manifestations in Marfan syndrome

AIMS

To investigate the natural history of mitral valve and aortic abnormalities in patients with Marfan syndrome during childhood and adolescence.

METHODS

Fifty two patients with Marfan syndrome were followed for a mean of 7.9 years. Occurrence of adverse cardiovascular outcomes was measured clinically and by ultrasound examination.

RESULTS

Mitral valve prolapse (MVP) was diagnosed in 46 patients at a mean age of 9.7 years, more than 80% of whom presented as "silent MVP". Mitral regurgitation (MR) occurred in 25 patients, aortic dilatation in 43, and aortic regurgitation (AR) in 13. Both MVP and aortic dilatation developed at a constant rate during the age period 5-20 years. In 23 patients MVP was diagnosed before aortic dilatation, in 18 the reverse occurred, and in 11 patients the two abnormalities were diagnosed simultaneously. During follow up, 21 patients showed progression of mitral valve dysfunction; progression of aortic abnormalities occurred in 13. Aortic surgery was performed in 10; two died of subsequent complications. Mitral valve surgery was performed in six. In sporadic female Marfan patients the age at initial diagnosis of MVP, MR, aortic dilatation, and AR was lowest, the grade of MR and AR most severe, the time lapse between the occurrence of MVP and subsequent MR as well as between dilatation and subsequent AR shortest, and the risk for cardiovascular associated morbidity and mortality highest.

CONCLUSIONS

During childhood and adolescence in Marfan syndrome, mitral valve dysfunction as well as aortic abnormalities develop and progress gradually, often without symptoms, but may cause considerable morbidity and mortality by the end of the second decade, especially in female sporadic patients.

The Marfan syndrome

The Marfan syndrome (MFS), initially described just over 100 years ago, was among the first conditions classified as a heritable disorder of connective tissue. MFS lies at one end of a phenotypic continuum, with people in the general population who have one or another of the features of MFS at the other end, and those with a variety of other conditions in between. Diagnosis of MFS and these other conditions remains based on clinical features. Mutations in FBN1, the gene that encodes fibrillin-1, are responsible for MFS and (in a few patients) other disorders in the continuum. In addition to skeletal, ocular, and cardiovascular features, patients with MFS have involvement of the skin, integument, lungs, and muscle tissue. Over the past 30 years, evolution of aggressive medical and surgical management of the cardiovascular problems, especially mitral valve prolapse, aortic dilatation, and aortic dissection, has resulted in considerable improvement in life expectancy.

[Surgical treatment of cardiovascular manifestations of Marfan's syndrome]

Patients with Marfan's syndrome suffer mainly from the cardiovascular manifestations of the disease, in particular the acute dissection or rupture of the dilated aorta. Due to improved diagnostic and early surgical intervention the life expectancy of these patients could be considerably improved. However, rupture is still the most frequent and dissection the second frequent cause of death. Life threatening complications of aortic dissection are pericardial effusion, aortic insufficiency and malperfusion syndrome, due to obstruction of aortic branches. Dissection of the ascending aorta is treated by implantation of a valved conduit with reimplantation of the coronary arteries. Some surgeons favor the complete replacement of the ascending aorta with preservation of the aortic valve, although long-term results show some development of aortic insufficiency after this procedure. Based on the experience of the last years, most surgeons prefer the prophylactic replacement of the aorta in Marfan patients, i.e. before complications have occurred. A special treatment algorithm helps to define the indication for the operative treatment in different manifestations of the disease. The low mortality of the elective replacement of the ascending aorta in contrast to replacement in emergency cases speaks in favor of the early operative treatment. For the long-term prognosis of the patient a closed and continuous cardiologic surveillance is mandatory. The patient should be close to a center with the necessary diagnostic tools and with sufficient experience with the medical and surgical treatment, in order to further improve the life expectancy in the future.

Aortic Root Replacement with Composite Graft: Experience in 95 Patients

Between January 1994 and June 1998, 95 patients with a mean age of 40.6 years (range, 23 to 69 years) underwent aortic root replacement with composite grafts. The operations were performed under hypothermia and cardiopulmonary bypass. In dissecting aortic aneurysm or aneurysms involving the aortic arch, selective cerebral perfusion via the right subclavian artery was employed, with additional femoral arterial cannulation if necessary. Combined procedures included partial arch replacement (6), elephant trunk technique (2), and mitral valve replacement (2). The mean duration of aortic crossclamping was 74.3 ± 17.9 min (42 to 133 min) and the mean duration of cardiopulmonary bypass was 117.8 ± 28.6 min (60 to 232 min). The hospital mortality was 1.1% (1 patient) and there was one late death. Complications comprised reexploration for bleeding (2), pericardial effusion (2), cerebral infarction (1), pleural effusion (1), and pneumothorax (1). Blood transfusion was not needed in 8 patients. Hemorrhage was the most dangerous complication. Suitable operative methods and improved techniques are the keys to successful aortic root replacement.

Novel exon skipping mutation in the fibrillin-1 gene: two 'hot spots' for the neonatal Marfan syndrome

The Marfan syndrome is an autosomal dominant heritable disorder of connective tissue that involves principally the skeletal, ocular, and cardiovascular systems. The most severe end of the phenotypic spectrum, the neonatal Marfan syndrome (nMFS), is characterized by pronounced atrioventricular valve dysfunction, and death often occurs within the first year of life due to congestive heart failure. Mutations in the gene coding for fibrillin-1, FBN1, are known to cause Marfan syndrome, and have been identified in almost all exons of FBN1. Here, we describe a novel mutation affecting the invariant + 1 position of the splice donor site in intron 31, associated with skipping of exon 31, in a patient with nMFS. Published reports of nMFS are reviewed and a strict definition for nMFS is suggested. If this definition is used, all nMFS mutations reported to date lie in one of two hot spots, comprising mainly missense mutations in FBN1 exons 24-27 and mutations causing skipping of exon 31 or 32.

Reduced penetrance and variable expressivity of familial thoracic aortic aneurysms/dissections

Autosomal dominant inheritance of thoracic aortic aneurysms and dissections occurs in subjects with Marfan syndrome, which results from mutations in the FBN1 gene on chromosome 15. A second chromosomal locus on 3p24-25 has been identified for a Marfan-like condition with thoracic aortic aneurysms. We describe here 6 families with multiple members with thoracic aortic aneurysms and dissections in the absence of the ocular and skeletal complications of Marfan syndrome. Medical records and autopsy reports on affected subjects in families with multiple members with thoracic aortic aneurysms and dissections were reviewed. Subjects in these families at risk for developing aortic disease underwent echocardiography to evaluate the aorta. The pattern of inheritance of thoracic aortic aneurysms and dissections was autosomal dominant in these families. Most affected subjects presented with aortic root dilatation or acute type I dissection, but the age of onset of disease was variable and there was decreased penetrance of the disorder. In 2 of the families, the syndrome was not linked to FBN1 or 3p24-25. Familial thoracic aortic aneurysm and dissection is an autosomal dominant condition with marked variability in the age of onset of aortic disease and decreased penetrance, making identification of affected subjects difficult. This condition is not due to mutations in the FBN1 gene or the unidentified gene on 3p24-25.

Surgical management of mitral regurgitation associated with Marfan's syndrome

BACKGROUND

The surgical treatment of mitral regurgitation associated with Marfan's syndrome remains controversial because of the underlying degenerative process.

METHODS

From October 1986 to June 1996, 33 patients with Marfan's syndrome underwent a mitral valve procedure. The mean age was 30 years (range, 2 to 55 years). Mitral regurgitation was caused by annulus dilatation in 2 patients, leaflet prolapse in 30 patients, and restricted leaflet motion in 1 patient. Mitral valve repair was performed in all patients except 1 who had mitral valve replacement.

RESULTS

Two patients died in the perioperative period. All survivors were available for follow-up, which ranged from 1 month to 122 months (mean follow-up, 39 months). There were three late deaths, two of which were related to aortic complications. The actuarial survival rate was 78.9% at 10 years. Freedom from mitral valve reoperation was 87.1% at 10 years. Echocardiographic studies were obtained in all survivors and showed absent or mild (1+) mitral regurgitation in 21 patients and moderate (2+) mitral regurgitation in 3.

CONCLUSIONS

Mitral valve repair for mitral regurgitation in patients with Marfan's syndrome can be performed safely in almost all instances. This technique provided stable midterm results comparable with those obtained for other degenerative mitral valve diseases.

A case of Marfan syndrome with acute monoblastic leukemia

We report on an 18-year-old man who had both acute monoblastic leukemia and Marfan syndrome. A diagnosis of Marfan syndrome was established by those characteristics of arachnodactyly, ectopia lentis, mitral valve prolapse, and mitral regurgitation. Findings on bone marrow examination of the patient showed that most of nucleated cells were monoblasts and immunophenotype of those cells showed CD13+, CD33+, CD56+, and HLA-DR+. To our knowledge, this is the second report of leukemia in Marfan syndrome in the world.

Mapping of X-linked myxomatous valvular dystrophy to chromosome Xq28

Myxoid heart disease is frequently encountered in the general population. It corresponds to an etiologically heterogeneous group of diseases, idiopathic mitral valve prolapse (IMVP) being the most common form. A rarely observed form of myxoid heart disease, X-linked myxomatous valvular dystrophy (XMVD), is inherited in an X-linked fashion and is characterized by multivalvular myxomatous degeneration; however, the histopathological features of the mitral valve do not differ significantly from the severe form of IMVP. In this article, we describe the genetic analysis of a large family in which XMVD is associated with a mild hemophilia A. The coagulation factor VIII gene position in Xq28 provided a starting point for the genetic study, which was conducted by use of polymorphic markers. Two-point linkage analysis confirmed this localization, and a maximum LOD score of 6.57 was found at straight theta=0 for two polymorphic microsatellite markers, INT-3 and DXS1008, the first one being intronic to the factor VIII gene. Haplotype analysis of this chromosomal region allowed the definition of an 8-cM minimal interval containing the gene for XMVD, between DXS8011 and Xqter.

Spectrum of structural abnormalities in floppy mitral valve echocardiographic evaluation

Posterior displacement of the mitral valve with billowing into the left atrium has been the major echocardiographic criterion used for the diagnosis of mitral valve prolapse (MVP). However, the current criteria are limited by the influence of hemodynamic factors on the degree of prolapse, whereas complications such as mitral regurgitation, endocarditis, and need for surgery have been associated with redundancy or thickening of the leaflets. Sixty-eight normal subjects (mean age, 40 years; range, 18 to 76 years) were compared with 58 patients with MVP (mean age, 37 years, range, 18 to 83 years). Leaflet displacement across the annular plane in the parasternal long-axis view was mandatory for the diagnosis of MVP. Transthoracic echocardiographic measurements of anterior and posterior leaflet thickness, leaflet length, and chordal length were made from the parasternal long-axis view and the mitral annular diameter, from the apical four-chamber and two-chamber views. The MVP group had greater anterior thickness (4.1 +/- 0.4 mm vs 5.3 +/- 0.7 mm; p = 0.0001), posterior thickness (3.2 +/- 0.4 mm vs 4.7 +/- 0.9 mm; p = 0.0001), anterior length (22.8 +/- 2.0 mm vs 25.7 +/- 1.7 mm; p = 0.0001), posterior length (12.8 +/- 1.0 mm vs 15.7 +/- 2.5 mm; p = 0.0001), chordal length (25.6 +/- 2.7 mm vs 28.0 +/- 2.5 mm; p = 0.0001), and annular diameter (29.1 +/- 1.5 mm vs 31.3 +/- 2.6 mm; p = 0.0001). Of the MVP group, >80% had at least one abnormality identified and >50% had at least two abnormalities. In addition, patients with MVP with significant regurgitation had greater anterior thickness (5.2 +/- 0.7 mm vs 5.8 +/- 0.8 mm; p = 0.015), posterior thickness (4.5 +/- 0.9 mm vs 5.3 +/- 0.7 mm; p = 0.024), posterior length (15.1 +/- 1.6 mm vs 17.9 +/- 4.2 mm; p = 0.004), and annular diameter (36.0 +/- 2.0 mm vs 33.3 +/- 2.1 mm; p = 0.0001). The majority of patients with floppy mitral valves resulting in MVP have structural abnormalities that may be defined by echocardiography. A spectrum of floppy valve structure is demonstrated by echocardiography, with mitral regurgitation occurring more frequently in patients with multiple and more severe anatomic abnormalities. In addition to the presence of prolapse and regurgitation, the assessment of leaflet thickness, leaflet length, annular diameter, and chordal length is fundamental to the definition and stratification of patients with MVP associated with the floppy mitral valve.

Marfan syndrome

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Revised diagnostic criteria for the Marfan syndrome

In 1986, the diagnosis of the Marfan syndrome was codified on the basis of clinical criteria in the Berlin nosology [Beighton et al., 1988]. Over time, weaknesses have emerged in these criteria, a problem accentuated by the advent of molecular testing. In this paper, we propose a revision of diagnostic criteria for Marfan syndrome and related conditions. Most notable are: more stringent requirements for diagnosis of the Marfan syndrome in relatives of an unequivocally affected individual; skeletal involvement as a major criterion if at least 4 of 8 typical skeletal manifestations are present; potential contribution of molecular analysis to the diagnosis of Marfan syndrome; and delineation of initial criteria for diagnosis of other heritable conditions with partially overlapping phenotypes.

Surgical management of Marfan syndrome in children

Between August 1983 and January 1991, seven patients with Marfan syndrome underwent surgery for severe cardiovascular complications. The mean age at presentation was 5.7 months (range 4 to 9 months) in the infant group (n = 3), and 13.3 years (range 10 to 16 years) in a group of older children (n = 4). The primary indications for surgery in the infant group (performed at a mean of 3 years after diagnosis) were ascending aortic aneurysm with valvar regurgitation in one patient, and severe mitral valve prolapse with regurgitation in two. In the older group, surgical indications (performed at a mean of 2.8 years after diagnosis) were ascending aortic aneurysm with valvar regurgitation in three patients and acute aortic dissection in one. For aortic surgery, a composite valved conduit was used in four patients, and an aortic homograft in one. For mitral valve surgery, mechanical prostheses were used. All patients survived the primary operation. Over a mean follow-up of 17.5 patient-years (range 1 to 9 years), two patients in the infant Marfan group went on to further successful surgery (prosthetic mitral valve replacement and aortic root repair with aortic homograft) at a mean interval of 4.3 years after the initial surgery. Our results suggest that the major cardiovascular risk factors of Marfan syndrome in the young, even in those diagnosed during infancy, have been favorably changed by surgery with an encouraging medium-term outlook. The correct timing of surgery is aided by echocardiography.

Cardiovascular manifestations of Marfan's syndrome: improved evaluation by transoesophageal echocardiography

OBJECTIVES

To assess the value of transoesophageal echocardiography in patients with Marfan syndrome particularly those with suspected aortic pathology or where conventional transthoracic imaging was suboptimal.

DESIGN AND PATIENTS

Eleven patients with Marfan syndrome. Seven patients were studied because of suspected aortic dissection and four because of inadequate transthoracic imaging.

INTERVENTION

Transoesophageal echocardiography and colour Doppler flow mapping by a 5 MHz single plane transoesophageal probe.

RESULTS

Aortic dissection was identified in six patients with subsequent diagnostic confirmation in all six. No dissection was found in one patient in whom the diagnosis had been suspected clinically. Estimates of aortic root dimensions and assessment of aortic and mitral valve pathology were made in four other patients with inadequate transthoracic imaging.

CONCLUSIONS

Transoesophageal echocardiography provides rapid diagnostic information in patients with Marfan syndrome with suspected aortic dissection and enhances the assessment of cardiovascular manifestations of this condition.

Mild dehydration induces echocardiographic signs of mitral valve prolapse in healthy females with prior normal cardiac findings

This study was designed to investigate the hypothesis that mitral valve prolapse (MVP) can be induced after diuresis in women without the abnormality who have characteristic body habitus. Fifteen tall, slim, healthy female volunteers with a normal cardiac findings, echocardiogram, and history were investigated after mild diuresis with furosemide and after placebo. All subjects lost weight after furosemide and placebo administration; but mean weight loss was significantly greater after furosemide administration than after placebo administration. Echocardiography showed MVP in none of the 15 patients before treatment, in seven after administration of placebo, and in seven after administration of furosemide. Coaptation point prolapsed superior to the anulus in seven subjects with echocardiographically determined MVP. Left ventricular end-diastolic dimensions decreased significantly after placebo or furosemide administration in subjects in whom MVP developed compared with the measurement in those in whom MVP did not develop. Murmurs characteristic of MVP disappeared in all four rehydrated subjects and echocardiographic changes resolved in two of the five rehydrated subjects. Thus echocardiographically determined MVP can be induced by mild dehydration in women with phenotypic body habitus of MVP; changes may resolve with rehydration. Results suggest an explanation for variable physical examination findings in persons with MVP.

Color flow and conventional echocardiography of the Marfan syndrome

Imaging and color flow Doppler echocardiography are an integral part of any evaluation of a patient with the Marfan syndrome. The major cardiovascular manifestations of this condition are aortic dilation, which may involve the proximal and distal aorta, aortic regurgitation, aortic dissection, mitral valve prolapse, and mitral regurgitation. Patients who have the Marfan syndrome should have serial echocardiograms to measure aortic root diameter carefully at the sinuses of Valsalva and subsequent levels (sinotubular junction, arch, descending and abdominal aorta). Additionally, color Doppler echocardiography assists in the diagnosis of aortic dissection and facilitates evaluation of the severity of aortic and mitral regurgitation that commonly complicate the Marfan syndrome. The risk of aortic dissection, which is the most serious manifestation of the Marfan syndrome, increases as the aorta enlarges. Therefore, elective composite graft surgery is recommended when the aortic root size reaches 60 mm, regardless of symptom status, or 55 mm in the presence of severe aortic regurgitation. Surgical replacement of the aortic root with a composite graft does not end the disease process. Color flow Doppler is useful in the diagnosis of dehiscence of the conduit sewing ring, coronary artery aneurysm, distal aortic dissections, and prosthetic valve dysfunction.

The Marfan syndrome: cardiovascular physical findings and diagnostic correlates

Correlations among cardiac symptoms and auscultatory and phonoechocardiographic findings in Marfan syndrome have not been completely defined. A total of 24 patients with Marfan syndrome (16 men and 8 women; mean age 28.2 +/- 8.6 years) were studied. Mitral valve prolapse was noted in 22, of whom 19 had either nonejection systolic click or mitral regurgitation murmur. Mitral regurgitation was noted in 12 patients by Doppler imaging. Aortic root dilatation was noted in 20 patients and aortic regurgitation in six, five of whom had aortic regurgitation murmur (5 of 20 patients had undergone surgery). Proximal aortic dissection was noted in two. Dyspnea (n = 12) was associated with progressive mitral or aortic regurgitation in four, but in the others dyspnea could not be explained by valvular or ventricular abnormalities. Chest pain was related to pneumothorax in five and aortic dissection in two but was not associated with either in 15 patients. Palpitations (n = 12) and lightheadedness (n = 6) were not associated with specific arrhythmias. In conclusion, mitral valve prolapse and aortic root dilatation were the most common cardiovascular abnormalities in Marfan syndrome. Mitral valve prolapse was frequently associated with typical auscultatory findings and symptoms including dyspnea, chest pain, palpitations, and lightheadedness, whereas aortic root dilatation could be clinically silent unless complicated by aortic regurgitation or aortic dissection.

Cardiac anomalies complicating congenital contractural arachnodactyly

A newborn boy with congenital contractural arachnodactyly (CCA) was found to have an atrial septal defect, ventricular septal defect, patent ductus arteriosus, and aortic arch anomalies. These resulted in congestive failure but subsequent progressive dilatation of both great arteries and development of aortic regurgitation were associated with eventual cardiorespiratory failure and death at 11.5 months. Others have noted that cardiac anomalies in CCA may be comparable with those of infantile Marfan's syndrome. Our case further extends the spectrum of cardiac abnormalities in CCA and substantiates that there is overlap with infantile Marfan's syndrome. This fact and our literature review suggest that early and complete cardiac assessment is necessary for appropriate management and evaluation of prognosis in any newborn infant with findings suggestive of either condition.

The Marfan syndrome--analysis of growth and cardiovascular manifestation

Forty-eight children and adolescents (mean age 10.5 years, range 1.25-18 years) with clinical evidence of Marfan syndrome were studied. Height and weight percentiles were established. Cardiac dimensions and morphology were studied by M-mode and 2D-echocardiography. At diagnosis left atrial and left ventricular end-diastolic diameter and left ventricular posterior wall thickness were within normal limits except in a few adolescent patients. Interventricular septum was thickened in about 20% and aortic diameter increased in 56% of the patients. An additional 13% of patients developed aortic dilation during the study period. At diagnosis regression analysis revealed a significant (P less than 0.05) correlation of the aortic diameter, septal thickness and the posterior left ventricular wall thickness and body surface area. Follow up studies of 19 patients allowed documentation of the development of aortic root dilation.

Mitral valve dimensions and motion in Marfan patients with and without mitral valve prolapse. Comparison to primary mitral valve prolapse and normal subjects

To determine mitral valve and extravalvular findings associated with mitral valve prolapse (MVP) in patients with the Marfan syndrome, we compared mitral leaflet and anular dimensions and motion by computerized two-dimensional echocardiography in 53 Marfan patients (28 with M-mode echocardiographic MVP) to those in 48 adults with primary MVP and in 35 normal subjects. Mitral leaflet billowing occurred in 28 of 28 Marfan patients with M-mode MVP versus 24 of 48 with primary MVP (p less than 0.00005), 0 of 25 Marfan patients without M-mode MVP, and 0 of 35 normal subjects (both, p less than 0.0001). Billowing occurred on the first systolic frame in 8 of 28 Marfan-MVP patients, in whom posterior leaflet chordae arose abnormally from the posterior ventricular wall, and in no other subjects. These patients had large mitral valves and normal anular dynamics, whereas the remaining 20 Marfan-MVP patients had increased systolic anular expansion. Marfan-MVP patients were younger than those without MVP (29 +/- 12 vs. 38 +/- 15 years, p less than 0.02) and had lower body mass index (19.8 +/- 2.7 vs. 23.9 +/- 2.9 kg/m2, p less than 0.00005) and systolic blood pressure (120 +/- 20 vs. 133 +/- 20 mm Hg, p less than 0.05), similar to differences between primary MVP and normal subjects in body mass index (21.5 +/- 3.0 vs. 23.9 +/- 4.8 kg/m2, p less than 0.01) and systolic pressure (118 +/- 14 vs. 125 +/- 18 mm Hg, p less than 0.05). Marfan patients with and without MVP had similar arm span, arm span to height ratio, upper to lower segment ratio, and prevalence of ectopia lentis and thoracic bony abnormalities, but arachnodactyly was more frequent in those with MVP (82% and 48%, respectively; p less than 0.02). We conclude that 1) leaflet billowing occurs more uniformly in Marfan patients with MVP than in primary MVP, 2) MVP in Marfan patients may be due to either valve enlargement with distinctively abnormal chordal architecture or abnormal mitral anular distensibility, 3) Marfan patients with MVP have low body weight and systolic blood pressure, similar to primary MVP, and 4) Marfan patients with MVP more commonly have arachnodactyly but otherwise have similar skeletal and anthropometric characteristics to other Marfan patients.

Pleiotropy revisited: molecular explanations of a classic concept

As commonly used, pleiotropy refers to multiple effects on phenotype of a single mutant gene. The importance of this concept to medical genetics has waxed and waned since its formulation soon after the rediscovery of Mendel's laws. Initially, the view that all aspects of a phenotype, and hence all manifestations of a mendelian syndrome, derive from a single function (or dysfunction) of a mutant allele gained ascendancy. Support for the importance of pleiotropy gradually diminished, and reached a low point in the 1940s with the one gene-one enzyme hypothesis. Studies of mammals and humans with heritable disorders of connective tissue sustained the notion that "genuine" pleiotropy probably did not exist. However, the demise of the relevance of pleiotropy was premature. Detailed understanding of gene organization, expression, and mutation indicates several mechanisms, such as multifunctional proteins, alternative splicing of messenger RNA, and overlapping coding sequences, through which genuine pleiotropy likely occurs in normal development and function, in mendelian syndromes, and in conditions due to somatic mutation. Furthermore, a broad definition of pleiotropy is warranted to subsume syndromes caused by abnormal function of contiguous genes, such as through large deletions, mutation of regulatory elements that coordinate expression, or less clearly understood "position effects." Thus, the use of pleiotropy in the context of aneuploidy syndromes is not inappropriate.

Marfan's syndrome: natural history and long-term follow-up of cardiovascular involvement

A retrospective analysis was undertaken to define the natural history and long-term follow-up of a group of patients with Marfan's syndrome. Eighty-four patients were diagnosed between January 1959 and June 1987 as having Marfan's syndrome; 68% were male; their ages ranged from 2 to 67 years (mean 26.6). Sixteen patients constituted the early surgical group (those who underwent surgery before 1979; mean age 36.1 years). Nineteen patients constituted the late surgical group (surgery in 1979 or later; mean age 33.3 years). The nonsurgical group comprised 49 patients (mean age 19.3 years). Fifty-seven percent of the patients had a diastolic murmur and 38% had cardiomegaly at presentation. Fifty-seven percent underwent cardiac catheterization, which revealed aortic root dilation (85%), aortic regurgitation (73%), aortic dissection (33%) and mitral regurgitation (36%). Thirteen of the 19 patients in the late surgical group received a composite graft repair of the ascending aorta as compared with only 2 of the 16 in the early surgical group. Follow-up information was obtained on 81 (96%) of 84 patients; the follow-up time was 2 to 332 months (mean 99). Thirty-one of the 81 patients died at age 3 to 63 years (mean age 35 years); 87% of the known causes of death were related to the cardiovascular system. Sixty-one percent of deaths were the result of aortic dissection or rupture or sudden cardiac death. Of the 50 survivors, 98%, including all patients in the late surgical group, were in functional class I or II. Overall survival at 5, 10 and 15 years after operation was 78.4%, 57.1% and 49.5%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurologic aspects of mitral valve prolapse

Mitral valve prolapse (MVP), the most frequently encountered valvular condition in the population, has been reported in an increasing variety of neurologic, muscular, and psychiatric disorders during the last twelve years. Extensive review of reports indicates this has resulted from observations of either (1) inordinate incidence of MVP in well-defined neurologic entities or (2) development of neurologic or ophthalmologic complications attributed to MVP. In the review presented, basis is found for categorizing MVP by its association with (1) well-defined, genetically determined neurologic disorders; (2) disorders characterized by structural abnormalities, many genetically determined, or inflammatory processes of connective tissues; (3) "mechanical" prolapse resulting from disproportion of mitral valve annulus and left ventricular size, which is, at times, reversible; and (4) a generally asymptomatic state that, at times, is associated with ischemic, thrombotic, embolic, and infectious disorders of the brain and eye. The paradox between the large number of persons with MVP in the general population who remain healthy and a subpopulation of patients with complications of MVP (eg, stroke) or other entities has been identified. A second paradox is found between the well-known increased incidence of MVP, especially in young patients with stroke, and the apparent rarity of stroke among patients with both common (eg, migraine) and unusual (eg, myotonic dystrophy) neurologic entities in which an extraordinary high prevalence of MVP is known to exist.

Comparison of cardiovascular and skeletal features of primary mitral valve prolapse and Marfan syndrome

The association of primary mitral valve prolapse (MVP) with thoracic bony abnormalities has led to the suggestion that MVP may be a forme fruste of the Marfan syndrome. Echocardiographic, skeletal and anthropometric findings in 59 subjects with primary MVP and 59 age- and sex-matched patients with Marfan syndrome were compared with those in 59 control subjects. Subjects with mitral prolapse were similar to control subjects and differed (p less than 0.025 to p less than 0.001) from the patients with Marfan syndrome in aortic root dimensions, height, arm span, upper/lower segment ratio and prevalences of arachnodactyly, scoliosis and pectus carinatum. Subjects with mitral prolapse and patients with Marfan syndrome had similar body mass indexes and prevalences of pectus excavatum and straight back. All 3 groups were similar in arm span/height ratio. The 5 subjects with MVP and arachnodactyly had lower weights, smaller body surface areas and smaller aortic root dimensions, and were more likely to have scoliosis than subjects with MVP without arachnodactyly. Thus, primary MVP differs from the Marfan syndrome in all major skeletal and cardiovascular features.

Genetic ascertainment with heterogeneous risk

Analysis of the bias of ascertainment is reformulated to deal with more general patterns commonly encountered in practice. The goal is to provide a unifying theory that will both replace the traditional, rather piecemeal, treatment of the problem and free it from certain restrictive assumptions. A compact algebraic method is furnished for analyzing the properties of the distributions by means of the probability generating function (PGF). The scope of the generalization is illustrated by applying it to the various classical patterns of bias of ascertainment. It is extended to other patterns in which the conditions of ascertainment, though more plausible, are also logically more complicated. It also accommodates cases hitherto inadequately dealt with, such as where the segregation ratios are heterogeneous (for example because of age-dependence); and cases where the ascertainment function is of arbitrary form and denies us such valuable, but demanding, assumptions as independence. Not only is the result unifying, but it leads to usable results in specific application such as diseases that depend on age or birth order. While the commonest applications are in human genetics, there are many other issues (such as the use of batteries of tests) in which it is equally important.

Spontaneous pneumothorax and mitral valve prolapse

We searched for mitral valve prolapse in patients with spontaneous pneumothorax to test the hypothesis that both may be part of a common disorder of connective tissue. Echocardiographic mitral valve prolapse was found in 11 (50 percent) of 22 patients who had suffered spontaneous pneumothorax compared to four (10 percent) of 40 age-matched control subjects (p less than 0.01). The body mass index (BMI) (weight/height2) was lower (p less than 0.001) in the group with pneumothorax; in five patients who were the thinnest in the study (BMI less than 2 standard deviations lower than mean normal value), mitral valve prolapse was present in four. The finding of a strong association of spontaneous pneumothorax with mitral valve prolapse, especially in subjects with an abnormal body build, suggests that in many patients, spontaneous pneumothorax may be a manifestation of a systemic abnormality of connective tissue.

Echocardiographic study of cardiac abnormalities in families of patients with Marfan's syndrome

Twelve patients (5 male and 7 female; mean age 17.7 +/- 12.3 years, range 5 to 42) with Marfan's syndrome and 48 of their first degree relatives (16 male and 22 female; mean age 29.8 +/- 17.3 years, range 4 to 60) were evaluated for cardiac abnormalities by echocardiography. Of the patients with Marfan's syndrome, aortic valve prolapse was present in 1, tricuspid valve prolapse in 4, mitral valve prolapse in 12 and aortic root dilation in 10. Of the 48 first degree relatives of these 12 patients, tricuspid valve prolapse was diagnosed in 3, mitral valve prolapse in 15 and aortic root dilation in 12; aortic valve prolapse was not observed in any of these subjects. Of the 60 persons studied in these 12 kindreds, 28 (47%) had cardiac involvement. Among the 28 with cardiac involvement, aortic valve prolapse was observed in 1 (3.5%), tricuspid valve prolapse in 7 (25%), mitral valve prolapse in 27 (96%) and aortic root dilation in 22 (79%). Mitral valve prolapse was also present in the seven subjects with tricuspid valve prolapse and one with aortic valve prolapse. In 32 of the 60 persons studied in the 12 families, at least one abnormality of the cardiac, skeletal or ophthalmologic system was observed. Nineteen subjects were younger than 18 years of age; all had cardiac involvement associated with Marfan's syndrome. The notably earlier presentation of cardiac involvement in young persons may be responsible for a shorter life span in this group.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitral valve prolapse in sickle cell disease: manifestation of a generalized connective tissue disorder

Previous studies have shown an association of sickle cell disease with generalized connective tissue disorders such as pseudoxanthoma elasticum. We recently documented an unexpectedly high prevalence of mitral valve prolapse, a connective tissue disorder, in sickle cell disease. To investigate this association, skin biopsies were analyzed from 32 sickle cell disease patients, 11 of whom had mitral prolapse. Total and type III collagen, collagen solubility, and uronic acid were not different between the patients with or without mitral prolapse (p greater than 0.05). Computerized morphometric quantitation of the volume fraction of elastic fibers was greater in sickle cell disease patients than in 10 normals (3.1 +/- 0.1 mean +/- SEM vs 2.0 +/- 0.3%; p less than 0.01) but less than in three patients with pseudoxanthoma elasticum (9.7 +/- 0.6%; p less than 0.001). Desmosine radioimmunoassay (an index of elastic fibers) was greater in sickle cell disease patients with mitral prolapse than those without (239.3 +/- 9.3 vs 171.7 +/- 25.4 ng/mg wet weight; p less than 0.02). Histopathologic grading showed a similar trend (p = 0.07). The combined probabilities of these three independent tests of elastic fiber quantity showed an increased elastic fiber concentration in mitral prolapse patients compared to those without mitral prolapse (p less than 0.02). Thus, there is no evidence for a specific collagen defect; rather, sickle cell disease appears to be associated with a spectrum of elastic tissue disorders, a feature that could predispose to mitral valve prolapse.

Relation of mitral valve prolapse to left ventricular size in Marfan's syndrome

Sporadic recent reports suggest that mitral valve prolapse (MVP) disappears with progressive left ventricular (LV) dilatation. To test this hypothesis, we sought to determine if an inverse relation exists between MVP and LV cavity size on M-mode echocardiograms in 83 patients with Marfan's syndrome. LV end-diastolic dimensions and presence or absence of MVP were determined. Forty-six patients had MVP. Of patients with an LV end-diastolic dimension less than or equal to 5 cm, 90% had MVP; only 19% of the 32 patients with abnormally large (greater than 5.8 cm) end-diastolic dimension had MVP. The prevalence of MVP in patients with an LV end-diastolic dimension of 5.1 to 5.8 cm was 69%. Thus, the prevalence of MVP was inversely related to LV cavity size. To determine whether appearance or disappearance of MVP was associated with decrease or increase in LV cavity size, serial echocardiograms from 67 patients (mean follow-up 42 months, range 3 to 99) were examined. These patients were separated into 3 groups based on changes in the LV end-diastolic dimension of greater than 1 cm over time. Group 1 consisted of 9 patients, all of whom had MVP and normal LV cavity size on their initial study. With subsequent increase in LV end-diastolic dimension (mean 1.42 +/- 0.3), MVP disappeared in 6 of the 9. Conversely, group 2 consisted of 4 patients, all of whom had dilated left ventricles on their initial echocardiogram and no evidence of MVP. After aortic valve replacement, the LV cavity size decreased (mean 2.3 +/- 0.7) and MVP appeared on follow-up studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of association between dermal arches and mitral valve prolapse: relation to anxiety

Mitral valve prolapse (MVP) has been reported to be associated with an increased frequency of dermal arches. To determine whether dermal arches are associated with MVP, 42 patients with echocardiographic (echo) MVP (probands) and 140 first-degree relatives in their families, including 48 with and 92 without MVP, were studied. Seventy-five, subjects with neither MVP nor blood relation to probands served as control subjects. Among the female probands, 6.9% had arches and among the males, 3.8% had arches. The proportion of arches was lower among female control subjects (4.0%) but higher among male control subjects (7.9%) (neither difference being significant [NS]). Among the relatives, 7.1% of the women with MPV and 4.6% of the women without MVP had arches (NS). Five percent of the men with MVP and 6.3% without MVP had arches (NS). No association existed between the occurrence of cardiovascular symptoms in patients and family members with MVP and presence of dermal arches, but a high proportion of probands with elevated trait anxiety without panic disorder had 4 or more dermal arches. These findings do not support a direct association of dermal arches with MVP.

The Marfan syndrome in early childhood: analysis of 15 patients diagnosed at less than 4 years of age

The clinical, cardiac and echocardiographic features were reviewed of 15 consecutive infants and children with the Marfan syndrome who presented at less than 4 years of age. The 10 females and 5 males were diagnosed at a mean age of 18 months (range 2 days to 3.5 years); 13 were followed up for a mean of 45 months (range 8 to 109 months) and 2 were lost to follow-up. On first evaluation, 5 patients had mitral regurgitation (MR) and none had aortic regurgitation (AR). Echocardiography showed aortic root dilatation in 9 and mitral valve prolapse (MVP) in 9; only 2 patients had a normal echocardiogram. At follow-up examination, all patients had aortic root dilatation; the rate of increase in aortic root diameter was generally greater than predicted on the basis of body surface area. One patient had AR at age 10 years. All 13 patients had MVP; 9 had progressive mitral valve dysfunction and 4 had mitral valve replacement. One patient died immediately postoperatively. Thus, aortic root dilatation is usually present in early childhood and serves as an objective indicator of the Marfan syndrome. MVP is common and MR, which may require valve replacement, is the leading cause of cardiovascular morbidity in childhood. Echocardiography is useful in the diagnosis and routine management of infants and children in whom the Marfan syndrome is suspected.