Transposition of the Great Arteries With Intact Ventricular Septum and Fetal-Onset Dilated Cardiomyopathy in a Neonate With a Homozygous NEXN Variant.

NEXN variants have previously been described as a cause of both pediatric- and adult-onset dilated cardiomyopathy but are not known to be associated with complex congenital heart disease. We report a case of an antenatal diagnosis of transposition of the great arteries with intact ventricular septum and fetal-onset dilated cardiomyopathy in a neonate with a loss-of-function homozygous frameshift variant in the NEXN gene, c.1589_1590del p.(Arg530Lysfs∗3). Both parents were found to be asymptomatic heterozygous carriers of the same variant at the time of diagnosis.