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New approach for genetic screening for syndrome linked to cardiac irregularities and sudden death
December 21, 2005Italian researchers have developed a novel approach for genetic screening for long QT syndrome (LQTS), an inherited disease that predisposes young individuals to cardiac arrhythmias and sudden death, according to a study in the December 21 issue of JAMA.
The clinical value of genetic testing has been demonstrated by the evidence that carriers of LQTS mutations lacking QT interval prolongation (certain measurement on an electrocardiogram), who therefore escape clinical diagnosis, have a 10 percent risk of major cardiac events by age 40 years whenever left untreated, according to background information in the article. In LQTS, disease severity and response to therapy vary according to the genetic mutation involved. There exists a critical need to devise more efficient genetic testing for LQTS.
Carlo Napolitano, M.D., Ph.D., of the S. Maugeri Foundation, Pavia, Italy, and colleagues performed genetic screening in patients with LQTS to determine the yield of genetic testing, as well as the type and the prevalence of mutations. The study involved genetic testing of 430 patients with LQTS and 1,115 family members between June 1996 and June 2004. The researchers confirmed their findings by testing for the identified mutations in a separate cohort of 75 patients.
The researchers identified 235 different mutations, 138 of which were new, in 310 (72 percent) of 430 patients. "The clinical value of molecular screening is influenced by the percentage of successfully genotyped individuals. Our data show that 70 percent of Romano Ward [a genetic mutation of LQTS] probands [an individual or member of a family being studied in a genetic investigation] can be successfully genotyped by standard methods based on the current knowledge about the molecular substrate of LQTS. This number, obtained in a population of consecutively genotyped patients, is high enough to support the introduction of genotyping into clinical medicine," the authors write.
"We have developed an approach to improve the efficiency of genetic screening for LQTS," the researchers write. "The novel strategy for LQTS genotyping may facilitate the access to genetic testing to a broader group of individuals, such as patients receiving drugs that prolong QT interval; family members of individuals with idiopathic ventricular fibrillation; and depending on results of further investigation, members of the general population to define the prevalence of known genetic variants of LQTS."
JAMA and Archives Journals
The researchers identified 235 different mutations, 138 of which were new, in 310 (72 percent) of 430 patients. "The clinical value of molecular screening is influenced by the percentage of successfully genotyped individuals. Our data show that 70 percent of Romano Ward [a genetic mutation of LQTS] probands [an individual or member of a family being studied in a genetic investigation] can be successfully genotyped by standard methods based on the current knowledge about the molecular substrate of LQTS. This number, obtained in a population of consecutively genotyped patients, is high enough to support the introduction of genotyping into clinical medicine," the authors write.
"We have developed an approach to improve the efficiency of genetic screening for LQTS," the researchers write. "The novel strategy for LQTS genotyping may facilitate the access to genetic testing to a broader group of individuals, such as patients receiving drugs that prolong QT interval; family members of individuals with idiopathic ventricular fibrillation; and depending on results of further investigation, members of the general population to define the prevalence of known genetic variants of LQTS."
JAMA and Archives Journals
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