Xq28-linked noncompaction of the left ventricular myocardium: prenatal diagnosis and pathologic analysis of affected individuals.

Isolated noncompaction of the left ventricular myocardium (INVM) is characterized by the presence of numerous prominent trabeculations and deep intertrabecular recesses within the left ventricle, sometimes also affecting the right ventricle and interventricular septum. Familial occurrence of this disorder was described previously. We present a family in which 6 affected individuals demonstrated X-linked recessive inheritance of this trait. Affected relatives presented postnatally with left ventricular failure and arrhythmias, associated with the pathognomonic echocardiographic findings of INVM. The usual findings of Barth syndrome (neutropenia, growth retardation, elevated urinary organic acids, low carnitine levels, and mitochondrial abnormalities) were either absent or found inconsistently. Fetal echocardiograms obtained between 24-30 weeks of gestation in 3 of the affected males showed a dilated left ventricle in one heart, but were not otherwise diagnostic of INVM in any of the cases. Four of the affected individuals died during infancy, one is in cardiac failure at age 8 months, and one is alive following cardiac transplant at age 9 months. The hearts from infants who died or underwent transplantation appeared, on gross examination, to be enlarged, with coarse, deep ventricular trabeculations and prominent endocardial fibroelastosis. Histologically, there were loosely organized fascicles of myocytes in subepicardial and midmyocardial zones of both ventricles, and the myocytes showed thin, often angulated fibers with prominent central clearing and reduced numbers of filaments. Markedly elongated mitochondria were present in some ventricular myocytes from one specimen, but this finding was not reproducible. Genetic linkage analysis has localized INVM to the Xq28 region, where other myopathies with cardiac involvement have been located.

Very long chain acyl-CoA dehydrogenase deficiency: successful treatment of acute cardiomyopathy.

Very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is a severe defect of mitochondrial fatty acid oxidation characterized by hypertrophic cardiomyopathy, pericardial effusion, steatosis, and hypoglycemia, often resulting in death by 4-5 months of age. The onset of cardiomyopathy and pericardial effusion is insidious and sudden, necessitating early diagnosis and intervention to prevent death. A family affected with this defect is described in which dietary therapy with medium-chain triglycerides (MCT) was associated with rapid reversal of these severe clinical symptoms. Diagnosis by acylcarnitine analysis in the neonatal period can provide the opportunity for early clinical intervention. Prenatal diagnosis from amniocytes by enzymology or in vitro analysis of the fat oxidation pathway with deuterated fatty acid precursors has also been successful and permits intervention at birth. Of 10 affected children, 7 untreated cases died within the first several months while the remaining 3 cases survived when treated with medium-chain triglycerides as the major source of dietary fat.