Newswise — 1. Muscle Mass Mainly Inherited
Researchers have discovered the specific genes that are responsible for a person's lean body mass. These results reveal that genetics—more than any other factor—determine what percent of a person's body mass is lean muscle.
Lean body mass is one of three major components of body weight; the other two are bone mass and fat mass. A lower percentage of lean body mass can lead to diminishing fitness and an increased risk for frailty, including osteoporosis in women.
"We can now identify the individual genes that underlie lean body mass," said Dr. Tim Spector of King's College London and principal author of the study. "This will allow us to understand how the body increases muscle mass, and may lead to new treatments for a variety of metabolic disorders."
The data examined in the present study were from the TwinsUK Adult Twin Registry, which studied over 3,000 female twins in the United Kingdom. In the study, the researchers used whole dual-energy X-ray absorptiometry (DXA) scans to accurately determine lean body mass, bone mass, and fat mass. The researches then accounted for age, body height, total fat, and bone mass. The results indicated that genes were approximately 65-percent responsible for total lean body mass.
Blood samples of the study participants revealed that the genes associated with body mass appear to be located on stretches of DNA found on chromosomes 12 and 14.
The researchers concluded that total lean body mass is highly heritable and independent of other body measures. This paper has been published online and will appear in the August 2007 issue of the Journal of Clinical Endocrinology & Metabolism, a publication of The Endocrine Society.
Title Linkage of Genes to Total Lean Body Mass in Normal Women
AuthorsGregory Livshits, Mernet S. Kato, Scott G. Wilson, and Tim D. Spector
2. In Vitro Fertilization Improves Childhood Growth and Metabolism
Not much is known about the long-term outcome of children born following in vitro fertilization (IVF) beyond the low risk of congenital abnormalities. However, a new study shows that these children may grow taller and have a healthier metabolism than other children in their age group. These improvements may be credited to subtle epigenetic alteration of imprinted genes or other genes that occur during the IVF process.
"This study is one of the first of its kind and demonstrates that differences are present by mid-childhood in children born following IVF treatment," said Harriet Miles, MD, of the University of Auckland in New Zealand and lead author of the study.
Researchers recruited 69 healthy children between the ages of 4 and 10 conceived using IVF and 71 naturally conceived control children. Researchers measured weight and body composition, bone age, insulin, lipid profile, and insulin-like growth factors. Findings from this study are similar to observations in animal studies, which show in vitro manipulation can result in persistent and possibly permanent metabolic alterations. This paper has been published online and will appear in the September 2007 issue of the Journal of Clinical Endocrinology & Metabolism, a publication of The Endocrine Society.
TitleIn Vitro Fertilization Improves Childhood Growth and Metabolism
AuthorsHarriet L Miles, Paul L. Hoffman, John Peek, Mark Harris, Dyanne Wilson, Elizabeth M. Robinson, Peter D. Gluckman, and Wayne S. Cutfield
3. New Patient Fact Sheet on Gestational Diabetes Available from Hormone Foundation
The Hormone Foundation, the public education affiliate of The Endocrine Society, has published a bilingual (English/Spanish) fact sheet on gestational diabetes. The fact sheet describes who is at risk and how to manage this condition to ensure the health of mother and child. It also provides information about the different treatment options and encourages regular monitoring of blood sugar to prevent complications.
This fact sheet is part of the award-winning Hormones & You series of monthly fact sheets. To download free copies visit the Foundation's Web site at http://www.hormone.org.
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