New discovery prevents symptoms of rare genetic disorder
December 1st, 2010
AMES, Iowa — A new study offers hope for children born with a rare genetic disease, according to a paper published by the American Association for the Advancement of Science.
The research was led by Dr. Matthew Ellinwood, a veterinarian and animal science professor at Iowa State University, in collaboration with Dr. Patricia Dickson at the Harbor-UCLA Medical Center, with colleagues at the Iowa State College of Veterinary Medicine, the University of Tennessee, St. Louis University and the University of Pennsylvania. Their work was published in the AAAS journal Science Translational Medicine.
The research focused on a disorder called mucopolysaccharidosis type I, or MPS I, which is caused by the lack of a key enzyme that breaks down substances the body needs to help build normal nerves, bone, cartilage, tendons, corneas, skin and connective tissue.
The researchers demonstrated that beginning replacement of the enzyme shortly after birth prevented irreversible damage caused by the disease. Previous studies on older subjects were only able to reduce MPS I symptoms with enzyme replacement therapy. Especially important was the prevention of clinical signs of brain, heart and bone disease.
"This study, for the first time, outlines the potential to fully treat mucopolysaccharidosis type I using current technology and medicines, and prevent what might otherwise be the fatal or seriously debilitating consequence of this inherited disease," Ellinwood said.
"This study will strengthen the need and demand for neo-natal screening for this rare disorder. Overall, we feel our discoveries outline tremendous improvements for the treatment of these sorts of rare genetic disorders generally and for the treatment of MPS I specifically," said Ellinwood, who has been studying the disease for 12 years in dogs, which also suffer from the disorder.
His past work helped identify a genetic mutation that led to a DNA testing program for the Schipperke dog breed that has for all practical purposes eliminated the disease.
There is no cure for severe forms of MPS I and similar disorders, which are collectively known as lysosomal storage diseases. Symptoms include clouding of eye corneas, skeletal deformities, heart valve disease and severe cognitive impairment and decline.
The research opens the door to improved methods of enzyme delivery in human patients with similar genetic disorders. It also suggests that babies could be tested for MPS I at the same time they are tested for other inherited diseases to determine if they need the enzyme replacement therapy.
"There is a test under development to identify children with MPS I at birth, allowing them access to treatment when it could do the most good. Currently, diagnosis is usually made after clinical signs of disease have already begun, and the rarity of the condition makes pre-natal diagnosis impractical," Ellinwood said.
MPS and related diseases are hereditary and almost without exception they are recessive, with a child receiving one mutant copy of the gene from each parent. Due to the recessive nature of the disease parents are unaffected, and have no way of knowing if they are carriers.
More information on these often fatal disorders is available from the National MPS Society Inc. website (http://www.mpssociety.org). The occurrence of MPS and related diseases in the general population is thought to be one in 25,000 births. The broader group of lysosomal storage diseases may occur as often as one in every 5,000 births.
More information about Ellinwood's work is available at: http://www.iastate.edu/Inside/2005/0415/ellinwood.shtml