Eating Disorders and Obesity: A Comprehensive Handbook

By Christopher G. Fairburn; Kelly D. Brownell | Go to book overview

5
The Molecular Genetics
of Body Weight Regulation

RUDOLPH L. LEIBEL

That genes exist for body weight and composition in animals is apparent from the autosomal recessive and dominant obesity mutations in rodents, transgenic experiments in mice, single gene mutations affecting muscle mass in cattle and sheep, and strainrelated differences in body composition in domesticated cattle, pigs, sheep, and other animals. The concordance of somatic phenotype among mono- and dizygous twins, and adopted children and their respective parents, as well as segregation analyses of relative adiposity in families, indicate a substantial genetic contribution to body fatness (see Chapters 3 and 4). Single gene/locus mutations that produce obesity in humans are also well documented (see below).


GENES AND BODY COMPOSITION

The genes determining fatness must affect energy intake, energy expenditure, or partitioning (the molecular form; e.g., fat, glycogen, and proteins in which calories are stored in the body). Such genes can affect all three of these major phenotypes or may affect only one or two of them. Body mass and composition reflect the lifetime effects of these three phenotypes, so small imbalances persisting over time can have large effects. Therefore, despite potent genetic influences on body fat, it is difficult to implicate specific genes in any but the rare instances of obesity that are inherited in Mendelian fashion.

Most observed Mendelian variation in phenotype is due to DNA sequence variation in a single gene. For non-Mendelian, complex or polygenic traits, phenotype variation reflects allelic variation in several or many genes and their interactions with each other and the environment. The recent applications of linkage analysis and positional cloning to Mendelian phenotypes have succeeded where the correlations between single-locus genotype and phenotype are strong, and where the effect of genotype is large.

-26-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this book

This book has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this book

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited page

Bookmark this page
Eating Disorders and Obesity: A Comprehensive Handbook
Table of contents

Table of contents

Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Full screen
/ 632

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.