What is Genetic Testing or Screening?
Genetic Testing is the direct examination of one’s DNA to identify specific gene mutations (mistakes) that are known to lead to diseases like Batten, Cystic Fibrosis, Muscular Dystrophy and others.
Why is Genetic Testing important?
[[Genetic testing plays a critical role in diagnosing diseases early enough to ensure that patients receive the most appropriate care, best available treatments, and support services. 7,12]]
Preconception genetic testing can also be useful in family planning, as each parent can determine if they are a carrier for an inherited disease like Batten
What does it mean to be a “carrier?”
Normally, every person has two copies of every gene, one inherited from each parent. Many (but not all) genetic diseases require two defective genes in order to develop; if one inherits one normal and one mutated gene, he or she does not have the disease but is a carrier and can pass the mutated gene onto their children.
Why screen for rare diseases? They’re rare and don’t affect many people.
While the incidence of each individual rare disease is low, these numbers add up: an estimated 25-30 million people in the United States are afflicted with one of more than 6,800 rare diseases, 80% of which are genetic. The worldwide incidence is estimated to be 350 million people – more than AIDS and cancer combined. 10
The History of Genetic Screening
[[Newborn screening began in the 1960s when Dr, Robert Guthrie developed a blood test for newborns that could detect phenylketonuria (PKU), a condition which leaves infants unable to break down the amino acid phenylalanine, causing serious symptoms like seizures and mental retardation.8 Fortunately, PKU is treatable with a restricted diet. However, most devastating genetic diseases do not have available treatments, making newborn screening “too little too late.11” In these cases, prevention is the key.]]
The first large-scale carrier screening came in the early 1970s, a time when 1 in 158 infants born in Cyprus were at risk for beta thalassemia, a life-threatening blood disorder. To address this issue, the government and Orthodox Church established a policy of mandatory carrier screening and counseling prior to starting a family.2 As a result, the disease has virtually disappeared from the Island.1
Rabbi Joseph Eckstein pioneered a similar program offering genetic screening to members of the Jewish community to eliminate Tay-Sachs and other genetic disorders common in the Jewish community. One in 27 Ashkenazi Jews are carriers for Tay-Sachs, but incidence in North America has dropped 90% since the start of the screening program.5,6,9
The Current State
[[Since the start of newborn screening for PKU, scientists have developed more tests to screen newborns for up to 60 different disorders. 6 However, states vary in the number (30-60), types of conditions, and quality of their testing protocols. Again, newborn screening does not prevent disease. It only serves to diagnose existing disease.]]
Carrier screening is available for more than 60 of the estimated 5,440 rare genetic diseases, but individual tests can range from $200 to $1,200, making these preconception carrier screenings cost-prohibitive for even the wealthiest families.6,11 Importantly, most affected infants are from families with no history of the disorder, so making carrier screenings more widely accessible is key to reducing the incidences of these genetic disorders.
Beyond Batten Disease Foundation Prevention Strategy
In the fall of 2008, Beyond Batten Disease Foundation founder Craig Benson and his colleagues approached National Center for Genome Resources researchers Stephen Kingsmore and Callum Bell with a challenge: to create a precise, inexpensive, genetic test capable of detecting hundreds of devastating genetic diseases, one that could be made widely available to parents in order to prevent the conception of children afflicted with devastating illnesses like Batten. Benson believed that recent improvements in DNA sequencing and robotic and sensor technologies and the dropping costs of these technologies made it the perfect time to develop such a test.
Where is Beyond Batten Disease Foundation’s screen now?
Kingsmore and his colleagues rose to Benson’s challenge, and in January 2011 they published the article “Carrier testing for severe childhood recessive diseases by next-generation sequencing” in Science Translational Medicine, one of the highest-ranking among more than 11,000 scientific and technology journals. Researchers demonstrated the test’s ability to detect mutations in 7,717 regions from 437 target genes that are responsible for 448 diseases. Amazingly, the screening is able to detect these mutations with an accuracy of 100%, the highest reported of any DNA testing platform.3,4 Since then, investigators have increased the number of diseases to over 600 and counting, beta-launched the platform as a diagnostic tool at Kansas City Children’s Medical Center, and were even featured in Time magazine’s top medical discoveries of 2012. 11 Plans are underway to commercialize the test and make it available internationally at a price of less than $2 per condition. A portion of the proceeds will ultimately come back to Beyond Batten Disease Foundation to fund research to treat and cure juvenile Batten disease.
For more information contact Kansas City Children’s Medical Center.