XQ28-LINKED NONCOMPACTION OF THE LEFT-VENTRICULAR MYOCARDIUM - PRENATAL-DIAGNOSIS AND PATHOLOGICAL ANALYSIS OF AFFECTED INDIVIDUALS

Isolated noncompaction of the left ventricular myocardium (INVM) is ch aracterized by the presence of numerous prominent trabeculations and d eep intertrabecular recesses within the left ventricle, sometimes also affecting the right ventricle and interventricular septum. Familial o ccurrence of this disorder was described previously. We present a fami ly in which 6 affected individuals demonstrated X-linked recessive inh eritance of this trait. Affected relatives presented postnatally with left ventricular failure and arrhythmias, associated with the pathogno monic echocardiographic findings of INVM. The usual findings of Barth syndrome (neutropenia, growth retardation, elevated urinary organic ac ids, low carnitine levels, and mitochondrial abnormalities) were eithe r absent or found inconsistently. Fetal echocardiograms obtained betwe en 24-30 weeks of gestation in 3 of the affected males showed a dilate d left ventricle in one heart, but were not otherwise diagnostic of IN VM in any of the cases. Four of the affected individuals died during i nfancy, one is in cardiac failure at age 8 months, and one is alive fo llowing cardiac transplant at age 9 months. The hearts from infants wh o died or underwent transplantation appeared, on gross examination, to be enlarged, with coarse, deep ventricular trabeculations and promine nt endocardial fibroelastosis. Histologically, there were loosely orga nized fascicles of myocytes in subepicardial and midmyocardial zones o f both ventricles, and the myocytes showed thin, often angulated fiber s with prominent central clearing and reduced numbers of filaments. Ma rkedly elongated mitochondria were present in some ventricular myocyte s from one specimen, but this finding was not reproducible. Genetic li nkage analysis has localized INVM to the Xq28 region, where other myop athies with cardiac involvement have been located. (C) 1997 Wiley-Liss , Inc.