Body & Brain

A genetic cause for small brains, heart links to HIV and calcium, and more in this week’s news

SMALL BRAIN Mutations in the NDE1 gene prevent cells from dividing normally, which may cause a severe reduction in brain size (lower row), shown here in MRI scans. Courtesy of Yale University School of Medicine
CTYPE html PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN” “http://www.w3.org/TR/REC-html40/loose.dtd”> Small brain mutation Mutations in a single gene are the cause of a rare genetic disorder that leaves children with a brain one-tenth the normal size, two international teams of researchers report April 28 in the American Journal of Human Genetics . To identify the mutations, researchers analyzed DNA from Turkish, Pakistani and Saudi Arabian families with children who had extremely underdeveloped brains. Affected children had mutations in a gene called NDE1 , both groups found. Cells without a working copy of the gene don’t correctly divide to form new cells, a defect that probably prevents the brain from growing normally in early development. Further studies of the gene might reveal clues to how humans evolved large brains, the researchers speculate. — Laura Sanders   Calcium linked to heart risks Researchers in Switzerland have correlated excess levels of calcium in the blood with a large and diverse set of risk factors for heart disease in a cross-section of 4,200 adults 35 to 75 years old. The strongest and most novel associations pointed to signs of oxidative stress. These markers included elevations in uric acid (responsible for gout), homocysteine (a marker of meat consumption) and the liver enzyme GGT. There’s no evidence that calcium consumption is itself a problem, the authors note in the April 21 PLoS One . Risks may trace instead, they say, to the body’s inappropriate management of the substance. — Janet Raloff   MS linchpin found in mouse tests A previously unknown kind of immune cell makes a protein that may be a pivotal player in multiple sclerosis, two studies in an upcoming issue of Nature Immunology show. The protein is an inflammation-causing immune agent called GM-CSF. In mice prone to MS-like disease, animals lacking the protein didn’t get sick, a Swiss team reports. Likewise, mice with a version of MS were cured of it when the GM-CSF protein was neutralized. A U.S. team also arrives at GM-CSF as a culprit in the disease and delineates how other immune cells and proteins appear to be involved in steps leading to MS, which is marked by an immune assault on protective sheaths that insulate nerves. —Nathan Seppa   HIV may increase heart failure risk People infected with HIV, the AIDS virus, may be more prone to developing heart failure, scientists report in the April 25 Archives of Internal Medicine . A study of more than 8,000 veterans who were monitored for a median of 7.3 years revealed 286 incidents of heart failure. The rate of heart failure incidents was 81 percent higher among HIV-positive participants. The U.S. team of researchers accounted for differences in age, race and ethnicity among the vets when conducting the analysis. Higher viral loads meant higher heart-failure risk, the scientists noted. — Nathan Seppa

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