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Introduction to
Genetic Testing
for Patients
Introduction to Genetic Testing for Patients
What are genetic disorders?
A genetic disorder is a medical condition that is caused
by changes in the genetic material called DNA
(deoxyribonucleic acid). DNA is organized into units
called genes, which are found within structures called
chromosomes (Figure 1). This genetic material is
passed down from one generation to the next. Genes
provide instructions that our bodies use to develop
and function. Each of us has two copies of our genes,
one copy that we get from our mother and one copy
from our father. Occasionally changes called mutations
may occur in one or more of our genes, which can lead
to a genetic disorder.
Figure 1
DNA
Chromosome
Gene
Cell
Nucleus
How do genetic disorders occur?
Genetic disorders can occur in different ways. In some cases, mutations may arise by
chance. This new or “de novo” mutation can be associated with a genetic condition in an
individual even if there is no family history of that particular condition. In other cases, genetic
disorders can be inherited or passed down from generation to generation. The chance
of passing on a genetic disorder within a family depends on the pattern of inheritance, or
manner in which a gene is inherited. The table below summarizes common patterns of
inheritance.
Patterns of Inheritance
• One genetic mutation, inherited from one parent, can cause disease.
Autosomal Dominant
• The chance for each child to inherit one mutation is 50%.
• Affects both males and females.
• Two mutations, one from each parent, can cause disease.
Autosomal Recessive
• The chance for each child to inherit two mutations is 25%.
• Affects both males and females.
• Genetic disease is caused by a mutation in a gene located on the X
chromosome. Females have two X chromosomes and males have one
X and one Y chromosome.
X-Linked
• Males are more frequently affected than females.
• Females have a 50% chance of passing the mutation to their children.
• Males have a 100% chance of passing the mutation to their daughters.
The mutation cannot be passed to their sons.
• Genetic disease is caused by a mutation located within the DNA of the
mitochondria, structures in cells that provide energy.
Mitochondrial Inheritance
• Mitochondrial mutations are inherited through females and are rarely
passed to the next generation through males.
• Mitochondrial diseases can affect both males and females.
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What is genetic testing?
Genetic testing is the analysis of one or more genes or chromosomes to detect changes
that are associated with genetic disease. A sample of DNA can be obtained within blood,
buccal (cheek) cells or other tissues. There are multiple genetic changes that are associated
with different types of genetic disorders. The specific genetic test needed will vary based on
specific circumstances.
What does GeneDx offer genetic testing for?
Cardiac Disorders
Neurological Disorders
Dermatologic Disorders
Ophthalmologic Disorders
Dysmorphology Disorders
Prenatal Diagnosis
Endocrine Disorders
Renal Disorders
Hematologic Disorders
Rheumatologic Disorders
Hereditary Cancers
Sex Differentiation Disorders
Immunologic Disorders
Skeletal Disorders
Metabolic Disorders
Whole Exome Sequencing (XomeDx)
Mitochondrial Disorders
Whole Genome Array (GenomeDx)
Who should consider genetic testing?
• A patient with a clinical diagnosis of a disease which can be genetic
• Family members of a patient who has a disease-causing mutation known to cause a
specific genetic disorder
• Parents may consider prenatal testing to detect genetic disease during pregnancy
based on family history, ultrasound findings or other factors
How is genetic testing helpful?
• To confirm the clinical diagnosis of a genetic disorder, especially when the condition is
clinically ambiguous
• To identify family members who are at risk of developing a genetic disorder
• To distinguish a genetic disorder from other conditions
• To make informed family planning decisions
Who is GeneDx?
GeneDx is a highly respected genetic testing company founded in 2000 by two scientists
from the National Institutes of Health to address the needs of patients and clinicians
concerned with rare genetic disorders. Currently, GeneDx offers testing for more than 400
genetic disorders, using DNA sequencing and deletion/duplication analysis of the associated
gene(s).
Why should your physician choose GeneDx?
No other laboratory has a level of service comparable to GeneDx. GeneDx has more than
14 years of experience in genetic testing for more than 400 disorders. GeneDx has a staff
of more than 70 geneticists and genetic counselors, who have extensive experience with
genetic testing and interpretation.
Introduction to Genetic Testing for Patients | 2
How can I order a genetic test from GeneDx?
Your physician can order a GeneDx test by taking the following steps:
1. Download the appropriate test requisition form from the GeneDx website:
www.genedx.com/forms
2. Complete all the forms with required information
3. Ship completed forms along with specimen to the following address:
Accessions
GeneDx
207 Perry Parkway
Gaithersburg, MD 20877, USA
4. As shipping requirements for clinical specimens vary by the country, please contact
your local carrier (FedEx, UPS, DHL office) for detailed information.
How can I pay for my genetic test?
Samples from outside the United States must be accompanied by full payment at the time of
sample submission. This can be accomplished by wire transfer, check, or credit card.
For large referring institutions, GeneDx can establish a monthly invoicing system after a
contract has been put in place.
For more information, please contact:
Adam Bennett
[email protected]
+1-301-519-2100 ext 6728
About GeneDx
GeneDx is a highly respected genetic testing company founded in 2000 by two scientists
from the National Institutes of Health (NIH) to address the needs of patients and clinicians
concerned with rare inherited disorders. GeneDx offers sequencing and deletion/duplication
testing for inherited cardiac disorders, mitochondrial disorders, neurological disorders,
inherited cancer disorders, and other rare genetic disorders. GeneDx also offers whole
exome sequencing, microarray-based testing, targeted mutation testing, and prenatal
diagnostic services. At GeneDx, our technical services are matched by our scientific
expertise and customer support. Our growing staff includes more than 100 geneticists and
genetic counselors specializing in clinical genetics, molecular genetics, metabolic genetics,
and cytogenetics who are just a phone call or email away. We invite you to visit our website
www.genedx.com to learn more about us and the services we offer.
207 Perry Parkway
Gaithersburg, MD 20877, USA
T +1 301 519 2100 • F +1 201 421 2010
E [email protected] • www.genedx.com
© 2016 GeneDx. All rights reserved. 91931 01/2016