Featured Research

from universities, journals, and other organizations

Researchers Discover Genetic Mutation For Rare Form Of Dwarfism

Date:
March 3, 1999
Source:
Johns Hopkins Medical Institutions
Summary:
A search for the genetic roots of towering height has led a Johns Hopkins endocrinologist to identify a mutation that causes a rare form of treatable dwarfism. Research results, published in the March issue of the Journal of Clinical Endocrinology and Metabolism, suggest that the mutation could be used as a prenatal screening test for the disorder.

A search for the genetic roots of towering height has led a Johns Hopkins endocrinologist to identify a mutation that causes a rare form of treatable dwarfism. Research results, published in the March issue of the Journal of Clinical Endocrinology and Metabolism, suggest that the mutation could be used as a prenatal screening test for the disorder.

After speaking at a meeting in Washington in 1996, Michael A. Levine, M.D., an authority on acromegaly -- a growth hormone disorder characterized by large hands and feet -- was invited by Brazilian researchers to consult on several families of giants seen at the University of S o Paulo Hospital clinic. There, Levine noticed two patients in the waiting area who were unusually small. While he continued to look for the genetic basis for the tall patients, he asked permission to start another study of the shorter ones.

By analyzing DNA samples, Levine, endocrinology instructor Roberto Salvatori, M.D., and an international team of collaborators went on to pinpoint the mutation responsible for dwarfism among at least 105 members of an extended family of Portuguese descent in Sergipe, a remote area in northeastern Brazil. The family comprises 23,000 individuals.

All of the affected family members, whose average height is three and a half feet, inherited defective genes that knock out the receptor for growth hormone releasing hormone (GHRHR). The tiny change in the genetic code for the receptor makes it impossible for chemical signals that stimulate growth of bones to be "heard"; therefore, bone growth is markedly impaired.

The study suggests that defects in the receptor may be a more common cause of growth hormone deficiency than previously suspected, Levine says.

"This family serves as a living laboratory for diagnostic tests and treatment to bypass the broken signaling pathways and restore growth hormone," says Levine, professor of pediatrics, medicine and pathology at Hopkins.

Twenty-two of the affected members studied underwent extensive endocrine evaluation. All had markedly reduced or undetectable blood concentrations of growth hormone. The levels of hormone did not increase in response to different stimuli.

Because the disorder is autosomal recessive for short stature, all affected family members received two copies of the altered gene -- one from each parent. The family has a high frequency of consanguineous marriages, with unions between first-degree cousins and between second-degree cousins relatively common.

In addition to short stature, the affected family members have high-pitched voices and increased amounts of abdominal fat. Except for a somewhat delayed onset of puberty, which did not affect their fertility, they did not manifest any signs or symptoms to suggest deficiency of other pituitary hormones.

In ongoing research since identifying the defective pathway, the researchers have been treating a subset of the population with recombinant human growth hormone. Each patient showed a brisk increase in speed of growth.

Levine and his colleagues are continuing their search for the cause of gigantism.

The work was supported in part by the National Institutes of Health and the Genentech Foundation for Growth and Development. Other institutions involved in the study were the University of S o Paulo, Brazil; Federal University of Sergipe, Aracaju, Brazil; Vanderbilt University, Nashville, Tenn.; and Northwestern University, Chicago.

--JHMI--

Relevant Web sites:

Little People of America: http://www.lpaonline.org/

Greenberg Center for Skeletal Dysplasia (at Johns Hopkins): http://www.med.jhu.edu/Greenberg.Center/Greenbrg.htm

Other research by Dr. Levine: http://www.med.jhu.edu/deptmed/resendo.html

A photograph of Dr. Levine and a study participant is available online: http://hopkins.med.jhu.edu/NewsMedia/press/1999/MARCH/990301.HTM


Story Source:

The above story is based on materials provided by Johns Hopkins Medical Institutions. Note: Materials may be edited for content and length.


Cite This Page:

Johns Hopkins Medical Institutions. "Researchers Discover Genetic Mutation For Rare Form Of Dwarfism." ScienceDaily. ScienceDaily, 3 March 1999. <www.sciencedaily.com/releases/1999/03/990302100905.htm>.
Johns Hopkins Medical Institutions. (1999, March 3). Researchers Discover Genetic Mutation For Rare Form Of Dwarfism. ScienceDaily. Retrieved September 16, 2014 from www.sciencedaily.com/releases/1999/03/990302100905.htm
Johns Hopkins Medical Institutions. "Researchers Discover Genetic Mutation For Rare Form Of Dwarfism." ScienceDaily. www.sciencedaily.com/releases/1999/03/990302100905.htm (accessed September 16, 2014).

Share This



More Health & Medicine News

Tuesday, September 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

EU Ministers and Experts Meet to Discuss Ebola Reponse

EU Ministers and Experts Meet to Discuss Ebola Reponse

AFP (Sep. 15, 2014) The European Commission met on Monday to coordinate aid that the EU can offer to African countries affected by the Ebola outbreak. Duration: 00:58 Video provided by AFP
Powered by NewsLook.com
Despite The Risks, Antibiotics Still Overprescribed For Kids

Despite The Risks, Antibiotics Still Overprescribed For Kids

Newsy (Sep. 15, 2014) A new study finds children are prescribed antibiotics twice as often as is necessary. Video provided by Newsy
Powered by NewsLook.com
FDA Eyes Skin Shocks Used at Mass. School

FDA Eyes Skin Shocks Used at Mass. School

AP (Sep. 15, 2014) The FDA is considering whether to ban devices used by the Judge Rotenberg Educational Center in Canton, Massachusetts, the only place in the country known to use electrical skin shocks as aversive conditioning for aggressive patients. (Sept. 15) Video provided by AP
Powered by NewsLook.com
Respiratory Virus Spreads To Northeast, Now In 21 States

Respiratory Virus Spreads To Northeast, Now In 21 States

Newsy (Sep. 14, 2014) The respiratory virus Enterovirus D68, which targets children, has spread from the Midwest to 21 states. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins