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Newswise In a study that began in a pair of infant siblings with a rare heart defect, Johns Hopkins researchers say they have identified a key molecular switch that regulates heart cell division and normally turns the process off around the time of birth. Their research, they report, could advance efforts to turn the process back on and regenerate heart tissue damaged by heart attacks or disease.

This study offers hope that we can someday find a way to restore the ability of heart cells to divide in response to injury and to help patients recover from many kinds of cardiac dysfunction, says cardiologist Daniel P. Judge, M.D., director of the Johns Hopkins Heart and Vascular Institutes Center for Inherited Heart Diseases. Things usually heal up well in many parts of the body through cell division, except in the heart and the brain. Although other work has generated a lot of excitement about the possibility of treatment with stem cells, our research offers an entirely different direction to pursue in finding ways to repair a damaged heart.

Unlike most other cells in the body that regularly die off and regenerate, heart cells rarely divide after birth. When those cells are damaged by heart attack, infection or other means, the injury is irreparable.

Judges new findings, reported online March 4 in the journal Nature Communications, emerged from insights into a genetic mutation that appears responsible for allowing cells to continue replicating in the heart in very rare cases.

The discovery, Judge says, began with the tale of two infants, siblings born years apart but each diagnosed in their earliest weeks with heart failure. One underwent a heart transplant at three months of age; the other at five months. When pathologists examined their damaged hearts after they were removed, they were intrigued to find that the babies heart cells continued to divide a process that wasnt supposed to happen at their ages.

The researchers then hunted for genetic abnormalities that might account for the phenomenon by scanning the small percent of their entire genome responsible for coding proteins. One stood out: ALMS1, in which each of the affected children had two abnormal copies.

The Johns Hopkins researchers also contacted colleagues at The Hospital for Sick Children in Toronto, Canada, who had found the same heart cell proliferation in five of its infant patients, including two sets of siblings. Genetic analysis showed those children had mutations in the same ALMS1 gene, which appears to cause a deficiency in the Alstrm protein that impairs the ability of heart cells to stop dividing on schedule. The runaway division may be responsible for the devastating heart damage in all of the infants, Judge says.

These mutations, it turned out, were also linked to a known rare recessive disorder called Alstrm syndrome, a condition associated with obesity, diabetes, blindness, hearing loss and heart disease.

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Researchers Find Protein 'Switch' Central to Heart Cell Division

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