Leveraging Innovative Technologies to
Solve a Medical Mystery
By Amanda Chase, PhD
December 7, 2020
Dilated cardiomyopathy (DCM) is a common cause of heart failure in children, and is also a common cause of heart transplantation for both adults and children. DCM occurs when heart muscle cells (cardiomyocytes; CMs) are damaged. Usually, the damaged muscle cells are in the left ventricle or the main pumping chamber. It results in an inability to pump blood as efficiently, a critical issue for the patient.
In some cases, DCM in kids can remain stable if treated well. However, when DCM progresses to a severe form, it requires a heart transplant. Ideally, patients can be treated to prevent progression to a severe condition that requires transplantation. Understanding the cause of the DCM can improve care for patients and, hopefully, decrease the need for transplantation.
This critical need was recently addressed by a group of Stanford investigators in collaboration with researchers at Ben-Gurion University, Israel, led by first author Aviva Levitas and senior author Ioannis Karakikes, Ph.D., Assistant Professor of Cardiothoracic Surgery. In a recent study, the researchers identified and functionally validated a new gene implicated in genetic DCM pathogenesis. This study was recently published in PLOS Genetics.
Several years ago, all five children from one family in Israel were diagnosed with early-onset, severe DCM, and eventually succumbed to the disease. Doctors suspected a genetic cause as over half of the DCM cases have been attributed to a familial link, that is, a mutation in genes that encode proteins involved in heart muscle (myocardium) function. Genetic testing did not provide any answers. The affected children did not carry any mutations in the 50 plus known genes associated with DCM. Like several families, they are learning that genetic sequencing will not deliver answers for everyone.
However, sequencing revealed that each child inherited two mutated copies, one from each parent, of a gene called SPEG – a gene not previously implicated in DCM. But no one could say whether this was the cause of the illness. Unlike pathogenic mutations that are known to cause disease or benign ones that do not, this type of mutation just is not understood enough to know if they are involved or not.
Directly assessing the pathogenicity of such mutations was, until now, challenging. By employing innovative technologies, such as human induced pluripotent stem cells (iPSCs) and CRISPR/Cas9-based genome editing technologies, the team developed an experimental platform to assess whether genetic mutations cause childhood cardiomyopathy and death. They found that the SPEG E1680K mutation found in the children disrupted normal physiology and function of iPSC-derived cardiac cells, providing direct evidence of pathogenicity that implicates a new gene encoding a kinase in the genetic etiology of the most common form childhood cardiomyopathies. This platform is especially useful for studying diseases that occur during fetal or early postnatal development stages (like many pediatric DCM cases) because they exhibit fetal-like phenotypes. This experimental approach can potentially be applied broadly as part of a clinically relevant investigation to systematically ascertain the pathogenicity of novel disease variants. This approach could help patients and future generations through improved screening, reproductive planning, and proper care for surviving family members.
Other Stanford Cardiovascular affiliated authors include Yuan Zhang, Isaac Perea Gil, Ricardo Serrano, Nashielli Diaz, Alexandra Gavidia, Michael Kapiloff, and Mark Mercola. Ben-Gurion University affiliated authors include Emad Muhammad Maram Arafat, Ruti Parvari, and Yoram Etzion.