Congenital heart diseases affect approximately one in 100 patients, making them the most common type of birth defect and the number-one cause of pediatric deaths. Now a new study showing that the mTOR inhibitor drug rapamycin can reverse cardiac muscle damage in a mouse model of the congenital disease LEOPARD syndrome not only identifies the first possible medical treatment for this rare condition, but also demonstrates the importance of targeted therapies in managing congenital diseases.
The findings in LEOPARD syndrome may additionally provide the first glimpse of a much broader implication — a potential mechanism for the treatment of other, more common congenital hypertrophy disorders
“The genetic mutations that alter the signaling pathways involved in cardiac development have been implicated in approximately 30 percent of the defects associated with congenital heart diseases,” explains the study’s senior author Maria Kontaridis, PhD, a scientist in the Division of Cardiovascular Medicine at BIDMC and Assistant Professor of Medicine at Harvard Medical School. “But the molecular underpinnings of these mutations have not been clear. This new work helps illuminate their complex biochemistry.”
Kontaridis’s lab investigates LEOPARD syndrome and Noonan syndrome, two of a cluster of congenital diseases known as “RASopathies,” which are the result of defects caused by mutations in genes in the RAS signaling pathway.
LEOPARD syndrome affects approximately 200 individuals worldwide and is clinically distinguished by multiple lentigines (freckle-like spots on the skin), as well as craniofacial defects, deafness, and blood abnormalities which can give rise to pediatric leukemias. Hypertrophic cardiomyopathy – a thickening of the heart muscle that typically leads to heart failure – is also associated with LS. With the exception of lentigines, Noonan syndrome patients exhibit nearly identical features and pathologies.