Clinical, pathological, and molecular analyses of cardiovascular abnormalities in Costello syndrome: a Ras/MAPK pathway syndrome.

Cardiovascular abnormalities are important features of Costello syndrome and other Ras/MAPK pathway syndromes ("RASopathies"). We conducted clinical, pathological and molecular analyses of 146 patients with an HRAS mutation including 61 enrolled in an ongoing longitudinal study and 85 from the literature. In our study, the most common (84%) HRAS mutation was p.G12S. A congenital heart defect (CHD) was present in 27 of 61 patients (44%), usually non-progressive valvar pulmonary stenosis. Hypertrophic cardiomyopathy (HCM), typically subaortic septal hypertrophy, was noted in 37 (61%), and 5 also had a CHD (14% of those with HCM). HCM was chronic or progressive in 14 (37%), stabilized in 10 (27%), and resolved in 5 (15%) patients with HCM; follow-up data was not available in 8 (22%). Atrial tachycardia occurred in 29 (48%). Valvar pulmonary stenosis rarely progressed and atrial septal defect was uncommon. Among those with HCM, the likelihood of progressing or remaining stable was similar (37%, 41% respectively). The observation of myocardial fiber disarray in 7 of 10 (70%) genotyped specimens with Costello syndrome is consistent with sarcomeric dysfunction. Multifocal atrial tachycardia may be distinctive for Costello syndrome. Potentially serious atrial tachycardia may present in the fetus, and may continue or worsen in about one-fourth of those with arrhythmia, but is generally self-limited in the remaining three-fourths of patients. Physicians should be aware of the potential for rapid development of severe HCM in infants with Costello syndrome, and the need for cardiovascular surveillance into adulthood as the natural history continues to be delineated.

Cardiac developmental defects and eccentric right ventricular hypertrophy in cardiomyocyte focal adhesion kinase (FAK) conditional knockout mice.

Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase that plays an important role in integrin-mediated signal transduction. To explore the role and mechanisms of FAK in cardiac development, we inactivated FAK in embryonic cardiomyocytes by crossing the floxed FAK mice with myosin light chain-2a (MLC2a) Cre mice, which expressed Cre as early as embryonic day 9.5 in the heart. The majority of conditional FAK knockout mice generated from MLC2a-Cre (CFKO-2a) died in the embryonic stage with thin ventricular wall and ventricular septal defects. A small fraction of CFKO-2a mice survived to adulthood with spontaneous eccentric right ventricle hypertrophy. Transmission electron microscopy analysis displayed swelling in the rough endoplasmic reticulum in CFKO-2a embryonic cardiomyocytes. We found that decreased cell proliferation, but not increased cell apoptosis or differentiation, is the reason for the thin ventricular wall in CFKO-2a mice. Microarray analysis suggests that myocyte enhancer factor 2a (MEF2a) can be regulated by FAK and that inactivation of FAK in the embryonic heart compromised MEF2a expression. Last, we found that Src, but not PI3K, is important in mediating signal transduction for the regulation of MEF2a by FAK. Together, these results identified the role and mechanisms of FAK in embryonic cardiac development.

The relationship of vascular glycolipid storage to clinical manifestations of Fabry disease: a cross-sectional study of a large cohort of clinically affected heterozygous women.

Fabry disease is a rare X-linked lysosomal storage disorder caused by deficient activity of alpha-galactosidase A (alpha-Gal A) resulting in the storage of glycosphingolipids, especially globotriaosylceramide (Gb3), in cells throughout the body, causing life-threatening renal, cardiac, and cerebrovascular complications in hemizygous males and some heterozygous females. Disease manifestations in heterozygotes are being recognized increasingly, but quantitative prospective data on their extent and severity are limited. Prospective clinical and laboratory assessments were performed in a 7-day study of 61 women with signs and symptoms of Fabry disease. Analyses included medical history and physical, neurologic, cardiac, and ophthalmologic assessments; laboratory assessments; renal function tests; magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) of the head; and Fabry-related blood and urine tests, including Gb3 levels in blood and urine, skin biopsies, and DNA genotype analysis of the alpha-Gal A gene to identify causative mutations. Quality of life, pain and concomitant medication were documented using validated questionnaires and diaries. All patients had normal Gb3 levels in plasma; only 1 patient had visible storage material in the superficial dermal vascular endothelial cells. Cardiac, renal, or cerebrovascular abnormalities were documented in 52 of the 57 patients (91%) with confirmed Fabry genotypes. These included electrocardiographic abnormalities in 38 of 52 patients (73%), echocardiographic abnormalities in 8 of 57 (14%), proteinuria (>150 g protein/24-h urine) in 23 of 38 (61%), low estimated glomerular filtration rate (<90 mL/min per 1.73 m) in 24 of 57 (42%), abnormal MRI in 4 of 54 (7%), and abnormal MRA in 10 of 50 patients (20%). Angiokeratomas and corneal epitheliopathy were documented in 63% and 82% of the 57 patients, respectively. Despite the virtual absence of storage material in plasma and skin vascular endothelial cells, this population of women with Fabry disease exhibited a wide spectrum of clinical abnormalities. Useful outcome measures for assessment of specific therapies need to be developed. Studies limited to homogeneously affected subjects may be possible.