Dec. 7, 1999 CHICAGO --- A newly found mutation in a gene that helps the body produce testosterone has been linked to Leydig cell adenoma, a rare testicular tumor that causes early puberty in boys.
The gene defect was identified by a research team headed by Andrew Shenker, M.D., of Northwestern University Medical School, and described in an article in the Dec. 2 issue of The New England Journal of Medicine.
The gene codes for a protein called luteinizing hormone (LH) receptor. Under normal conditions, the LH receptor receives a message from the pituitary gland and signals Leydig cells to make testosterone and initiate puberty.
In the mutated form, the LH receptor causes rapid growth (hyperplasia) of Leydig cells and overproduction of testosterone without the hormonal signals normally required from the pituitary.
Other defects in the same gene, earlier identified by Shenker and others, have been implicated in a different, inherited form of precocious puberty in boys. Here also, the malfunctioning LH receptor causes Leydig cells to multiply and make testosterone independent of signals from the pituitary.
The LH receptor is a member of a family of proteins called G-coupled protein receptors. Mutations in the genes that code for these proteins recently have been recognized as a cause of endocrine diseases.
"The effects of different mutations of the LH receptor gene may further understanding of the signal pathways involved in progression from hyperplasia to tumor growth in endocrine tissues," Shenker said.
He also said that the study of naturally occurring signaling defects not only has inherent value in understanding the molecular basis of disease, but also helps scientists understand the basic mechanisms involved in cell communication.
Shenker is an assistant professor of pediatrics and of molecular pharmacology and biological chemistry at the Medical School, a researcher at the Children's Memorial Institute for Education and Research and a member of The Robert H. Lurie Comprehensive Cancer Center of Northwestern University.
His co-researchers were Guoquan Liu, Lise Duranteau, M.D., and Jason Monroe of Northwestern University Medical School and the Children's Memorial Institute for Education and Research; Jean-Claude Carel, M.D., Hopital Saint Vincent de Paul, Paris; and Daniel A. Doyle, M.D., Temple University Children's Medical Center, Philadelphia.
This study was supported by grants from the American Cancer Society and the National Institutes of Health, a Lavoisier Grant from the French Ministry of Foreign Affairs and a grant from the Philippe Foundation, Inc. Shenker is the Crown Family Young Investigator in Developmental Systems Biology at Children's Memorial Institute for Education and Research.
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