Researchers Test First Universal Newborn Screening For Fragile X Syndrome - Rush University Medical Center

Main Category: Pediatrics / Children's Health
Also Included In: Medical Devices / Diagnostics;  Genetics;  Psychology / Psychiatry
Article Date: 14 Sep 2008 - 0:00 PST

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Rush University Medical Center will be launching the first systematic newborn screening program for the genetic mutation that results in fragile X syndrome - the single most common known genetic cause of autism and mental retardation.

For the first time, a blood test has been developed that can identify the fragile X mutation using small drops of blood collected from infants after birth. The test developed by researchers at UC Davis in Sacramento Calif., and validated by researchers at Rush, is part of a $2.3 million study funded by the National Institutes of Health (NIH). All newborns at Rush and UC Davis will undergo the screening with the goal of screening as many as 30,000 infants during the next five years.

The NIH-funded study will lay the groundwork for universal newborn screening of all infants in the U.S. for early detection of the fragile X mutation.

"The study will allow families to learn in early infancy whether their child will have the disorder," said Dr. Elizabeth Berry-Kravis, one of the world's leading experts on fragile X and related conditions, pediatric neurologist at Rush and study co-investigator. "This new test could potentially pave the way for early identification and intervention for all children diagnosed with fragile X."

"While the newborn screening study is not specifically designed to offer treatment, the diagnosis will open the door to new therapies for infants," said Dr. Randi Hagerman, study senior investigator and medical director of the M.I.N.D. Institute at UC Davis. "Once we have identified affected infants, we will propose treatment options for them."

Children with fragile X syndrome suffer from physical anomalies, intellectual deficits, learning disabilities, and behavioral and psychiatric problems that are not diagnosed right away.

Current diagnostic tests for fragile X are limited by expense and could not be offered as newborn screening tests.

The new test employs an inexpensive polymerase chain reaction (PCR) technique that amplifies the expansion of the FMR1 gene, allowing researchers to detect the number of nucleotide repeats, from normal number of repeats to the full fragile X mutation of 200 repeats or more.

Fragile X syndrome and its associated disorders are the result of a mistake in the number of repeats of three nucleotides in the FMR1 gene on the X chromosome. A normal X chromosome generally has up to 55 repeats of these trinucleotides. Repeats above 200 result in fragile X syndrome.

"With the test, we not only can identify affected infants, but also assess the gene's impact on other family members," said Dr. Berry-Kravis. "Most families don't realize the gene mutation exists and how it can impact the health of other family members."

Individuals who have between 55 and 200 repeats of nucleotides are carriers and are susceptible to a wide range of ailments, like premature ovarian failure and fragile X-associated tremor/ataxia syndrome (FXTAS). FXTAS is a condition affecting older males and some older females that is routinely mistaken for Parkinson's disease or other movement disorders.

Males tend to be more severely affected by fragile X than females because women have two X chromosomes. If one of a woman's chromosomes has a fragile X mutation, the second X chromosome can compensate.

"The significance of universal newborn screening is amplified by the fact that adults related to children with fragile X syndrome often suffer from associated, but frequently misdiagnosed ailments," said Dr. Berry-Kravis.

For a newborn screening tool to be effective, it has to be accurate, quick, inexpensive, and work on a very small amount of DNA. The new blood spot test responds to all of those requirements.

Screenings will begin in the fall of 2008.

About the Fragile X Syndrome Clinic at Rush

The Fragile X Syndrome clinic at Rush is dedicated to the care of children with Fragile X syndrome, an X-chromosome-linked condition that is the most common inherited cause of mental retardation. The clinic is the only one of its kind inChicagoand one of few in theMidwest.

The fragile X clinic at Rush was started in 1991 to serve the unique needs of the fragile X population. The clinic maintains affiliations with specialists in pediatrics, neurology, genetics, optometry, child psychology, special education/education psychology, speech and language, occupational therapy and dentistry who have experience working with individuals with fragile X syndrome.

About Rush University Medical Center

Rush University Medical Center is an academic medical center that encompasses the more than 600 staffed-bed hospital (including Rush Children's Hospital), the Johnston R. Bowman Health Center and Rush University. Rush University, with more than 1,270 students, is home to one of the first medical schools in the Midwest, and one of the nation's top-ranked nursing colleges. Rush University also offers graduate programs in allied health and the basic sciences. Rush is noted for bringing together clinical care and research to address major health problems, including arthritis and orthopedic disorders, cancer, heart disease, mental illness, neurological disorders and diseases associated with aging. http://www.rush.edu/rumc/page-1124119148908.html

Rush University Medical Center