Health Scan: 'Lean genes' affect body mass

Understanding lean mass is important because it can dwindle with age, leading to reduced fitness and greater frailty.

By JUDY SIEGEL-ITZKOVICH
scale 88 (photo credit: )
scale 88
(photo credit: )
Genes have a strong influence on how much lean body mass a woman has, according to a new twin study by Tel Aviv University researchers published online in the Journal of Clinical Endocrinology and Metabolism. Lean body mass, fat mass and bone mass are the three major components of body composition, says Dr. Gregory Livshits and colleagues who conducted the research. But while much is known about the genetics of fat mass and bone mass, as well as their effects on health and fitness, less data are available on lean mass. Understanding lean mass is important, the researchers add, because it can dwindle with age, leading to reduced fitness and greater frailty. To understand the role of genes in lean mass, the scientists evaluated 3,180 British women, including 509 pairs of identical twins and 1,081 fraternal twin pairs. Such twin studies allow scientists to separate out the effects of heredity and environment, as identical twins share all their genetic code while fraternal pairs share only half of their genes. Height was strongly linked to lean mass, the researchers found, while total fat mass and bone mineral density made a weaker but still significant contribution. After adjusting the data to account for the influence of other factors, the researchers found that genetic factors accounted for 65.2 percent of the variation in total lean body mass. The researchers also performed genome scans on all of the fraternal twins to identify genes that could influence lean mass. They identified candidates on chromosomes #12 and #14. "Replication studies from other populations followed by fine mapping should be the next step in identifying the individual genes involved, which could have important physiological effects on bone and fat as well as muscle," the researchers conclude. ANOTHER HERZOG AT YAD SARAH Although his mother, Aura Herzog, volunteered with Yad Sarah and even borrowed equipment when she fell at home as First Lady, Welfare and Social Services Minister Isaac Herzog was not intimately familiar with the voluntary organization when he visited its Jerusalem headquarters recently. But he was so impressed by what he saw that he kept asking questions of director-general Yehudit Intract. The organization, founded 31 years ago by now-Jerusalem Mayor Uri Lupolianski to lend medical equipment to the needy, has over 5,000 volunteers and more than 100 branches, and has expanded it services to teaching the elderly and disabled how to use computers, providing dental treatment, offering explanations of medical problems to the layman, emergency beepers, tabletop gardening for the disabled, play services for disabled children, laundry services for the incontinent and many others. Even though helping people function at home rather than be hospitalized saves the economy hundreds of millions of shekels a year, Yad Sarah receives little state help. During his 90-minute tour, Herzog promised to examine the possibility of tightening cooperation between his ministry and Yad Sarah, given its well-trained volunteers and branches around the country. BLIND REMEMBER ORDER OF WORDS AND OBJECTS Blind people are usually good at recalling things in the right order, according to research conducted at The Hebrew University of Jerusalem and published in Current Biology. The study by Noa Raz and Ehud Zohary showed that mental capabilities may be refined to compensate for the lack of visual input. The researchers tested the performance of 19 congenitally blind individuals and matched sighted controls in two types of memory tasks. In the item-memory tasks, subjects were asked to identify 20 words from a list. In the serial-memory tasks, subjects had to remember not only the words, but their ordinal position. Those who were blind recalled more words than the sighted, and many in their original order.