Genetic testing

Genetic testing that provides greater diagnostic certainty with important prognostic and therapeutic implications for many diseases.

Also known as DNA testing, allows the determination of bloodlines and the genetic diagnosis of vulnerabilities to inherited diseases.

It refers to the analysis of chromosomes (DNA), proteins, and certain metabolites in order to detect heritable disease-related genotypes, mutations, phenotypes, or karyotypes for clinical purposes.

In population ecology, it can be used to track genetic strengths and vulnerabilities of species populations.

Can be used to determine a child’s parentage, or in general a person’s ancestry or biological relationship between people.

It studies chromosomes to the level of individual genes, and includes biochemical tests for the possible presence of genetic diseases, or mutant forms of genes associated with increased risk of developing genetic disorders.

GT can identify changes in chromosomes, genes, or proteins.

Previously, the main genetic tests searched for abnormal chromosome numbers and mutations that lead to rare, inherited disorders.

Genetic tests have expanded to determine the risk of developing specific diseases or disorders, with the more common diseases consisting of heart disease and cancer.

Such testing can confirm or rule out a suspected genetic condition or help determine a person’s chance of developing or passing on a genetic disorder.

Several hundred genetic tests are currently in use.

Genetic mutations can directly affect the structure of the proteins they code for, therefore testing for specific genetic diseases can also be accomplished by looking at those proteins or their metabolites, or looking at stained or fluorescent chromosomes under a microscope.

Genetic testing provides information about a person’s genes and chromosomes throughout life.

Genetic testing include:

Cell-free fetal DNA (cffDNA) testing is a non-invasive (for the fetus) test. It is performed on a sample of venous blood from the mother, and can provide information about the fetus early in pregnancy.

Cell-free fetal DNA (cffDNA) is the most sensitive and specific screening test for Down syndrome.

Newborn screening: is used just after birth to identify genetic disorders that can be treated early in life.

In all states by law neonatal gene testing is required for at least 21 disorders.

A blood sample is collected with a heel prick from the newborn 24–48 hours after birth and sent to the lab for analysis.

All states currently test infants for phenylketonuria and congenital hypothyroidism.

Genetic testing is used to confirm a diagnosis when a particular condition is suspected based on physical mutations and symptoms.

Diagnostic testing can be performed at any time during a person’s life, but is not available for all genes or all genetic conditions.

Carrier testing is used to identify people who carry one copy of a gene mutation that, when present in two copies, causes a genetic disorder.

Carrier testing is offered to patients who have a family history of genetic disorder or to people of certain ethnic groups with increased specific genetic disorders.

Preimplantation genetic diagnosis refers to genetic testing procedures that are performed on human embryos prior to the implantation as part of an in vitro fertilization procedure.

Prenatal diagnosis detects changes in a fetus’s genes or chromosomes before birth.

Prenatal diagnosis testing is offered to couples with an increased risk of having a baby with a genetic or chromosomal disorder.

Prenatal genetic testing methods include an amniocentesis, which removes a sample of fluid from the mother’s amniotic sac 15 to 20 or more weeks into pregnancy.

The amniotic fluid is then tested for chromosomal abnormalities such as Down syndrome (Trisomy 21) and Trisomy 18.

This method is 99.4% accurate at detecting and diagnosing fetal chromosome abnormalities.

The miscarriage rate associated with an amniocentesis, is only 1/400.

Chorionic villi are projections from the placenta that carry the same genetic makeup as the baby, and is another prenatal genetic test.

A sample of chorionic villi is removed from the placenta to be tested.

This test is performed 10–13 weeks into pregnancy and results are ready 7–14 days after the test was done.

Another test using blood taken from the fetal umbilical cord is percutaneous umbilical cord blood sampling.

Available for familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon carcinoma.

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