Incomplete Shone’s complex as a rare cardiac manifestation of Coffin–Lowry syndrome: a case report

Abstract

Coffin-Lowry syndrome is a rare X-linked genetic disorder caused by pathogenic variants in the RPS6KA3 gene, characterized by distinctive craniofacial features, skeletal abnormalities, and neurodevelopmental impairment. Although cardiac involvement has been reported in Coffin-Lowry syndrome, it most commonly manifests as cardiomyopathy or valvular insufficiency. To the best of our knowledge, Coffin-Lowry syndrome has not been associated with obstructive left-sided congenital heart diseases including an incomplete Shone’s complex. We report a case of a 2-month-old boy who, on cardiac evaluation, was found to have coarctation of the aorta, a bicuspid aortic valve with severe stenosis, a parachute-like mitral valve with mild subvalvular stenosis, consistent with an incomplete Shone’s complex, and marked left ventricular hypertrophy. The patient underwent successful corrective surgery for coarctation of the aorta and aortic valve stenosis, with follow-up revealing moderate residual aortic valve stenosis and mild residual valvular dysfunction. Genetic testing identified a maternally inherited microduplication of the X chromosome p22.12 region, encompassing several 5′ exons of the RPS6KA3 gene. This case suggests that obstructive left-sided congenital heart diseases including an incomplete Shone’s complex may represent a previously unrecognized cardiac manifestations of Coffin–Lowry syndrome, thereby expanding the cardiovascular phenotype of this rare condition. Recognition of this association may have implications for early diagnosis, genetic evaluation, and long-term cardiac surveillance in affected patients.