People with Laron syndrome lack certain receptors important for body growth. They have normal levels of growth hormone produced by the pituitary gland, but without the cell receptors, the hormone is unable to bind to cells and promote growth.
Research presented June 12 at the 79th Annual Meeting of the Endocrine Society in Minneapolis suggests that scientists studying Laron syndrome and other types of diseases in which growth hormone has been implicated could use the new mouse model to develop a drug that would work in the absence of a growth hormone receptor.
"We set out to disrupt a mouse growth hormone receptor gene to test whether the disruption of that gene would result in a dwarf mouse, and it did," said John Kopchick, Goll-Ohio Professor of molecular biology at Ohio University and principal investigator on the research project. "Now we have what we believe is the first mammalian model for this human disease."
There are about 200 reported cases of Laron syndrome, which was first identified in 1966. People with the disorder, also known as Laron dwarfism, usually develop symptoms at or shortly after birth. Studies suggest the incidence of Laron syndrome is higher in girls than in boys, although scientists aren't sure why. In addition to a short stature, people with the syndrome sometimes have deep set eyes, smaller hands and feet and a high-pitched voice, and may be prone to obesity.
Treatment of Laron syndrome with human growth hormone is ineffective because people with the disease lack the receptors they need to use the growth hormone. The mouse model could be particularly useful to scientists interested in developing drugs that act downstream of the growth hormone receptors, Kopchick said.
These drugs might have potential for treatment of a variety of growth hormone-related diseases, including Laron syndrome and other forms of dwarfism, and will be useful in establishing the importance of growth hormone as it relates to other disease indications such as diabetic retinopathy, diabetic nephropathy and some forms of cancer.
Ohio University has applied for a U.S. patent on the technology. The work was supported by the State of Ohio's Eminent Scholar Program, the Ohio Department of Development Thomas Edison Program and Sensus Drug Development Corp.