Scientists Study Dense-Boned Family

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Scientists Study Dense-Boned Family

Wed May 15, 5:28 PM ET

By JEFF DONN, Associated Press Writer

BOSTON (AP) - Scientists studying a family with a strange and rare genetic

condition that gives members square jaws and superdense bones have

pinpointed a protein that could advance the quest for better osteoporosis

drugs.

Current treatments for osteoporosis, like calcium and hormones, largely

focus on preventing bone loss. But doctors are looking for better ways to

actually build bone, especially in patients with severe loss.

Bone-weakening osteoporosis affects 10 million Americans ‹ most of them

women ‹ and leads to more than 1.5 million fractures a year, according to

the National Institutes of Health (news - web sites).

Researchers at Yale University focused on a family with the opposite

problem: bones about twice as dense as usual. Their genetic condition is so

rare it is unnamed.

It gives family members square jaws and bony growths on the roofs of their

mouths. It does not impair their daily lives, other than making it difficult

to float.

The condition was discovered in the family when a middle-aged member got

into a serious traffic accident.

" They took routine X-rays, and he had unbelievably dense bones ‹ no

fractures, " said Dr. Lifton, leader of the research team.

The researchers, who reported their findings in Thursday's New England

Journal of Medicine (news - web sites), first found that the family members

all carried a mutation of a gene known as LRP5. They were also found to have

unusually high levels of bone-building proteins.

The researchers then located a specific protein, called Dkk-1, that appears

to act as a brake on the bone-building chemical process set in motion by

LRP5.

They reasoned that if the Dkk-1 protein could be altered by a drug so it no

longer brakes this bone-building process, osteoporosis patients could form

new bone.

" What's so exciting about this is it points to a system that seems to build

bones, " said Dr. Karl Insogna, a bone specialist on the research team. " It

provides a direct molecular target. "

Already, at least one drug developed for osteoporosis seems to build bone,

but it is not clear exactly how it works.

In an accompanying editorial, two doctors at Baylor College of Medicine in

Houston, Millan Patel and Gerard Karsenty, cautioned that more study is

needed to know if it is practical to disable the Dkk-1 protein.

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On the Net:

http://www.nejm.org for New England Journal of Medicine

http://www.niams.nih.gov/hi/topics/osteoporosis/opbkgr.htm for background on

osteoporosis