Creatine Transporter Defect
Identified in 2001, X-linked Creatine Transporter Defect (CTD) is an inherited error of metabolism that inhibits the body's ability to supply sufficient levels of creatine to the brain via the creatine transporter. Caused by a defect in the X-linked creatine transporter, CTD results in mental retardation with symptoms including speech and language impairment, short attention span, and low IQ. Due to the fact that CTD has only recently been identified, the true incidence rate of the disease has not yet been determined.
The Avicena Group, together with the University of Cincinnati Medical Center and the Cincinnati Children's Hospital Medical Center, is at the forefront of research into treatments for CTD. The groups have initiated a pilot study to assess the potential of creatine supplementation to restore levels of creatine in the brain and to enhance cognitive function in CTD patients. In addition, a model that will allow the rapid screening of new therapies is being developed in collaboration with the University of Cincinnati.
What is CTD
Identified in 2001 by researchers at the University of Cincinnati, CTD is an inherited disease that causes mental retardation. Due to an error in metabolism caused by a defective X-linked gene, CTD prevents the successful transport of sufficient levels of creatine to the brain via the creatine transporter. Without the necessary levels of creatine to support brain function, individuals suffer from symptoms such as speech and language impairment, short attention span, and low IQ.
CTD has been shown to affect both males and females. However, the severity of the mental retardation is significantly magnified in male patients due to the fact that the defect is located on the X-chromosome, of which males have only one.
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Types of CTD
Due to its relatively recent identification, researchers are just beginning to develop a better understanding of CTD. As such, the disease has not yet been categorized into different types.
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Symptoms of CTD
The most common symptoms associated with CTD are severe speech and language impairment, short attention span, and low IQ. Additional symptoms may include epilepsy and autistic behavior.
Based on the fact that the disease is a defect of the X chromosome, the severity of symptoms is significantly increased in male versus female patients.
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Progression of CTD
CTD is an inherited disease that is present at birth. The natural progression of CTD is not yet completely understood and is presently the focus of scientific investigation.
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Diagnosis of CTD
CTD is presently diagnosed using either magnetic resonance imaging (MRI) examination, or through DNA analysis.
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Causes of CTD
CTD is caused by a genetic defect present on the X chromosome that is linked to the body's creatine transporter. This defect directly impairs the body's ability to deliver sufficient levels of creatine to the brain.
Due to the presence of the defect on the X chromosome, male patients completely lack the ability to transport creatine into their brain cells. Female CTD patients, who possess one healthy X chromosome, are able to deliver limited amounts of creatine into their brain cells. However, the level of creatine present in their brain cells is significantly less than that of individuals who do not suffer from CTD.
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Incidences of CTD
CTD affects both males and females, although male patients will develop significantly more severe symptoms compared to female patients.
To date, researchers have only identified a few isolated cases of the disease. That being said, researchers expect that increased screening will reveal a significant increase in the number of confirmed CTD cases. This increase will likely be attributed to prior misdiagnoses of various diseases with symptoms similar to CTD.
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Treatment of CTD
As a result of its relatively recent identification, researchers are just now beginning to investigate potential treatments for CTD. Current research efforts are focused on identifying and developing methods to successfully deliver creatine or analogs to the brain in order to restore normal brain functions. Findings to date indicate that CTD may be successfully treated if diagnosed early.
The Avicena Group, together with Dr. Ton DeGrauw of the Cincinnati Children's Hospital Medical Center and Dr. Joe Clark of the University of Cincinnati Medical Center, has initiated a pilot study to assess the potential of creatine supplementation to restore levels of creatine in the brain and to enhance cognitive function in CTD patients. In addition, a model that will allow the rapid screening of new therapies is being developed in collaboration with the University of Cincinnati.
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