RNA interference therapy heals growth deficiency disorder in a l...( A team of Vanderbilt researchers hav...)

A team of Vanderbilt researchers have demonstrated for the first time that a new type of gene therapy, called RNA interference, can heal a genetic disorder in a live animal.

The study, which was published online Nov. 15 by the journal Endocrinology, shows that RNA interference can rescue a strain of mouse that has been genetically engineered to express a defective human hormone that interferes with normal growth. When the gene that produces the defective human growth hormone is inserted into the mouses genome, it also stunts the mouses growth. But when a small snippet of RNA that interferes with the hormones production is also added, the mouse is restored to normal.

It has been very satisfying to figure out the underlying cause of this genetic disorder and then identify a way to prevent it, says John Phillips, the David T. Karzon Professor of Pediatrics at the Vanderbilt University Medical Center, who has been studying human growth deficiency disorders since 1978. He collaborated on the research with graduate students Nikki Shariat and Robin Ryther, who are directed by Professor of Biological Sciences James G. Patton.

Growth hormone deficiency has been estimated to occur in between one in 4,000 to 10,000 children. It has a number of different causes, but one that is genetically inherited is called Isolated Growth Hormone Deficiency type II, and this is the subject of the study.

Children with IGHD-II appear fairly normal at birth but do not gain weight or grow as fast as they should, and their bones do not mature properly. The current treatment consists of daily injections of growth hormone for years until the patients reach their adult height. Not only is this treatment extremely expensive, it also fails to correct the underlying source of the problem: deterioration and death of cells in the pituitary gland that produce growth hormone. As a result, this single hormone deficiency can develop into multi-hormonal deficiency over time.

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