How is a genetic test performed?
(source: Iowa Institute of Human Genetics)
Step 1– In the doctor’s office:
- Your doctor or genetic counselor will talk to you about the test, what it may or may not tell you, insurance coverage, and risks of insurance discrimination
- You may have to sign a consent form depending on the lab performing the test.
- Your doctor or nurse will get a sample from you. Samples are usually blood samples, but sometimes can be saliva, skin, fluid around the baby during pregnancy, or tumor.
- You may be asked to give another sample if the first sample does not work.
- The sample is sent to the lab.
Step 2– Prepare your DNA
- The lab will get your DNA from the sample to test.
- To find the cause of a disease, the lab can use different ways to look at all or part of your DNA. The way the lab looks at your DNA will depend on the type of genetic test your doctor ordered.
Step 3– Sequencing your DNA
- Sequencing tests read your DNA and look for variants (changes) in the DNA.
- Sequencing tests can give detailed information about:< >Specific genes and DNA variants (targeted sequence capture)All of the genes that make proteins in a person (whole exome sequencing)All of the DNA in your genome (whole genome sequencing). The human genome is made of DNA and contains all of a person’s genetic information (like a set of books).The lab may put all or part of your DNA on a machine called a DNA sequencer.
- The DNA sequencer reads your DNA and collects data known as short “reads.” Each “read” represents a very tiny part of your total DNA sequence (each read is like a page in a book).
Step 4– Analyzing your DNA
- Computers are used to put all of the pieces (reads) of your DNA together (like putting the pages of the book in the right order).
- Computers are used to compare your DNA to all of the DNA in the human body (the human reference genome).
- The lab gets a report from the computers, which lists any variants in your DNA.
- We all have DNA changes (variants)
- Some DNA variants cause disease (like a word spelled wrong); other variants do not cause disease (like a word with different spellings: grey and gray).
- We do not know what every DNA variant means at this time.
Step 5– Interpreting your DNA
- A team of experts talks about and analyzes your results. Doctors, scientists, genetic counselors, and computer experts are all on the team (like a group of people sitting down to read and talk about a book).
- To decide which variant causes the disease you are interested in, the team looks at your results (your list of variants), your symptoms, and your family history.
- The team may or may not be able to find the cause of the disease you are interested in.
- If the team finds the cause of the disease, they confirm the result with a different test.
- Some reasons why the team may not be able to find the cause of the disease can be:
- Some parts of the DNA cannot be sequenced.
- Not enough is known about the disease at this time.
- The test that was performed did not look at the part of your DNA that is causing the disease, and a different test needs to be ordered.
- The team was not given enough information about your symptoms or family history to interpret the results.
Step 6– Receiving your results
- The lab will give the written results back to your doctor or genetic counselor. Results of clinical tests will go in your medical record. Research study results do not go in your medical record.
- Your doctor and/or genetic counselor will tell you the results and answer your questions.
- Your doctor may need to perform more medical or genetic testing based on the results of your test.
- The amount of time to get your test results can vary.
Genetic Testing Information and Directions
Genetic Testing for the PPA used to be provided by Dr. Frank Lehmann-Horn’s lab in Ulm, Germany. Since 2015, the testing has been transferred to Fullerton Genetics Labs in Asheville, North Carolina, USA. Please follow the following link for instructions on how to order this testing.
Please refer to the bolded PERIODIC PARALYSIS information at the top of the page after you click on the link above. International samples should be accepted.
If you have questions about this testing process, a representative at Fullerton Labs should be able to help you. If you should need further assistance, please contact Ms. Linda Feld, PPA Genetic Testing Liaison, at PPA Inquiries.
A second possibility is to do your genetic testing with Strongbridge. They provide a full test for Periodic Paralysis. For more information click here.
The PPA endorses Fullerton Genetics Lab as our preferred lab for genetic testing of periodic paralysis. However, we provide other options as we become aware of them. We like our members to have choices. Please CONTACT US if you are aware of other labs not listed here.
Other Genetic Testing in United States
PreventionGenetics is a leader in providing comprehensive genetic testing. Testing for Primary Periodic Paralysis includes three types: Hyperkalemic Periodic Paralysis, Hypokalemic Periodic Paralysis, and Andersen-Tawil Syndrome. The full gene sequencing methods for these disorders reduce the number of false negative results. Our experienced team provides flexible billing options, fast turnaround times, personalized service and the highest quality testing. PreventionGenetics is a nationally and internationally accredited laboratory.
Website: Prevention Genetics
Link for Clinical Inquiries / Genetic Counselor assistance: firstname.lastname@example.org
Genetic Testing in Europe
The following lab offers genetic testing for periodic paralysis for people living in the European Union:
CeGaT GmbH in Tübingen