TYPES OF GENETIC TESTING Genetic tests use various laboratory methods to examine your DNA. They range from studying a single letter of the DNA sequence to analyzing the entire genome.
The HudsonAlpha Clinical Services Lab, The Smith Family Clinic for Genomic Medicine and companies on the campus of HudsonAlpha, provide many of these tests.
Prenatal: There are two types of prenatal tests related to genetic conditions: screening and diagnostic. Prenatal screening tests
generally measure the concentration of specific proteins or hormones in the mother’s bloodstream to identify the risk of having a child with certain genetic disorders, such as Down syndrome. Recent noninvasive techniques are even able to collect and test pieces of fetal DNA that circulate in the mother’s blood. These approaches do not diagnose a disorder, but signal that further testing should be considered. Diagnostic tests directly analyze fetal DNA, often obtained through invasive procedures such as amniocentesis or chorionic villus sampling (CVS). Prenatal diagnostic tests may study the number
Wellness:
and structure of the chromosomes in fetal cells, or identify the sequence of a specific gene or region of the genome.
Genetic testing to identify lifestyle and wellness-related traits is an emerging field. These tests provide information on topics ranging from earwax type and personality style to nicotine dependence and muscle performance. Since many of these traits are influenced by multiple genetic and environmental factors, the accuracy and utility of these tests is unclear.
Pediatric: Between two and three percent of all children have a physical birth defect or clinical disorder. These may be seen at birth, or become evident
during childhood. All infants born in the United States undergo newborn screening to identify disorders that can affect a child’s long-term health. Using a few drops of blood from a baby’s heel, clinical laboratories test for at least 29 diseases, most of which are genetic in nature. Children who have symptoms of a genetic disorder or do not meet developmental milestones may undergo diagnostic genetic testing to identify or rule out a specific condition. This may be a targeted test for a specific mutation, a test of a single gene or a handful of genes known to be associated with the child’s symptoms, or a genome-wide analysis to more broadly search for answers.
Adult:
Genetic testing in adults generally falls into one of three categories:
Diagnostic testing seeks to identify disease-causing mutations to explain a patient’s existing set of symptoms. Predictive/Presymptomatic testing detects mutations for disorders that often appear later in life. These tests are usually ordered for individuals who have a family history of a disease but have no signs of that disease at the time of testing. Carrier testing identifies people who carry a single copy of a mutation that - when present in two copies – causes disease. The individual is healthy but could pass along the mutation to a child. Couples may decide to have carrier testing to determine their risk of having a child with certain genetic conditions.
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