Skip Navigation
Home / Patient Resources / Genetic Carrier Screening

Contact Us | Schedule an Appointment | Directions

Johns Hopkins MedicineFertility Center
About Us|Our Team|Conditions|Infertility Services|Research|Education|Patient Resources|Financial Info
JHM dome
 
Overview
Preparing for a Procedure
Support Groups
Counseling
Genetic Counseling
Genetic Carrier Screening
Top Image
Patient Resources
Genetic Carrier Screening
Print This Page

At the time of your appointment we will be asking you some questions about your family history and ethnic background. There are several genetic conditions that are more common in specific ethnic groups.  The information below briefly reviews some general information about testing for these conditions. If you have questions about this information, please address them with the doctor during your scheduled appointment. 


What are genes?
Genes are made up of a chemical called DNA and are the codes or instructions that tell the body how to grow and develop.  These genes are arranged on strings of information called chromosomes. We have two copies of each chromosome, one that is inherited from our mother and one that is inherited from our father; as a result, we have one copy of each gene.

What are recessive diseases?
Many conditions are now known to be caused by changes, or mutations, in genes.  Some genetic conditions, known as recessive conditions, are caused when a change or mutation is present on both genes of a pair.  This means that both the mother and father must pass on the same changed gene in order for a child to have a recessive condition.

What is a carrier?
A carrier is a person who has a change in only one gene of a pair and the other gene of the pair is working normally.  A carrier is sometimes said to have the disease trait but has no physical symptoms of the disease.  In many families, a recessive gene change or trait can be passed on through generations without ever being known.  A recessive disease can only occur if a person who is a carrier has a baby with another person who is also a carrier.  Such a couple would have a 1 in 4 (25 percent) chance, in each pregnancy, of having a baby with that recessive disease.

Who should be screened?
DNA tests are available to help a couple determine if they are carriers of the same recessive disease trait and are at risk for having children with that recessive condition. Some diseases occur more often in certain ethnic groups.  Information about the carrier frequency of the more common recessive disease traits in certain ethnic groups is provided below.  There are many other recessive conditions, not listed below, for which testing is not typically performed because the conditions are less common or because testing is not available.

ETHNICITY

DISEASE

CARRIER FREQUENCY

Ashkenazi Jewish:

Tay-Sachs

1/30

Canavan

1/40

Cystic fibrosis

1/29

Familial Dysautonomia

1/30

Mediterranean:

Thalassemia

1/20-1/50

Sickle cell anemia

1/30-1/50

European Caucasian:

Cystic fibrosis

1/29

African American:

Sickle cell anemia

1/10

Thalassemia

1/30-1/75

Cystic fibrosis

1/65

Asian:

Thalassemia

1/20-1/50

Cystic fibrosis

1/90

Hispanic:

Cystic fibrosis

1/46

French Canadian:

Tay-Sachs

1/15

Cystic fibrosis

1/29


Is there prenatal testing?
If both parents are determined to be carriers of mutations for the same disease, a prenatal test is available to determine if the baby has that recessive disease.  At some IVF centers in the country preimplantation genetic diagnosis (PGD) may be available to test an embryo for a genetic disorder before that embryo is transferred into the mother’s uterus.

How can I have carrier testing?
If you are interested in learning more about the genetic conditions more common in your specific ethnic group and the availability of carrier testing for these conditions, please ask the genetic counselor during your scheduled counseling session, or speak to your obstetrician.  You may also wish to check with your insurance company about whether this testing would be covered under your plan.

 

Contact Us | Maps and Directions | Privacy Policy

About Johns Hopkins Medicine - Baltimore,  Maryland 

INFERTILITY SERVICES:  Infertility Testing    ][ : In Vitro Fertilization (IVF)    ][ Blastocyst Culture and Transfer][    Embryo and Sperm Cryopreservation    ][    Donor Eggs    ][    Gamete Intrafallopian Transfer (GIFT)    ][    Intracytoplasmic Sperm Injection (ICSI)    ][    Intrauterine Insemination (IUI)    ][    Transmyometrial Embryo Transfer (Towako)    ][    Zygote Intrafallopian Transfer (ZIFT)    ][    Gestational Carrier -- Surrogacy Program 

©2008 The Johns Hopkins University and Johns Hopkins Health System, All Rights Reserved