Screening
It’s important to be screened before you start or add to a family. If both you and your partner are carriers, there are many more options available to you before pregnancy than there are once you’re already pregnant. Watch this brief video for an explanation of the screening process.
IMPORTANT UPDATE: SCREENING NOW RECOMMENDED FOR ANYONE PLANNING TO HAVE A CHILD.
In previous recommendations, the Canavan Foundation, following the guidance of professional associations such as the American College of Obstetricians and Gynecologists (ACOG) and the American College of Medical Genetics and Genomics (ACMG), suggested that those of Ashkenazi (Eastern European) Jewish origin, and/or a family history of Canavan disease, be prioritized for screening for Canavan disease and other Jewish genetic diseases, due to the higher prevalence of the Canavan mutation in those populations. These recommendations have since been updated.
Given the recent advances in screening technology and updated recommendations from the most respected professional organizations, the Canavan Foundation now recommends that anyone planning to have a child be screened for a wide range of genetic conditions – including Canavan disease – preferably before conception. A doctor or genetic counselor can help you understand which particular tests you should consider.
Preconception screening for Cystic Fibrosis and Spinal Muscular Atrophy (SMA) is recommended for anyone who is considering starting or adding to a family, no matter what their ancestry.
Expanded Carrier Screening
The past years have seen a rapid change in genetic carrier screening. Technological advances have made it possible to screen for many different diseases simultaneously, at a greatly reduced price. Concurrently, many more genetic mutations linked to specific diseases have been identified.
This has led to what is generally called “Expanded Carrier Screening,” where both the number of diseases for which screening is possible has dramatically increased, and the number of people for whom screening is recommended has also greatly expanded, to include anyone planning to have a child.
Previously, screening recommendations were based primarily on ethnic or geographic origin (e.g. Tay Sachs in Ashkenazi Jews, sickle-cell disease in African-Americans, thalassemia in those of Mediterranean or Southeast Asian origin) or family history of genetic disease. Screening recommendations were based on an individual’s particular risk factors, taking into account the expense of the tests.
Now, most professional societies, including the American College of Medical Genetics and Genomics (ACMG) and the American College of Obstetricians and Gynecologists (ACOG) recommend that anyone planning to start or add to a family be offered a broad list of tests, with ethnic/geographic origin and family history taken into account, but no longer the sole basis for recommendations.
Expanded carrier screening also takes into account current societal changes, where couples of mixed background make up an increasing portion of the population, and knowledge of specific family origin and genetic history have become less clear or reliable.
What is Genetic Carrier Screening?
Genetic carrier screening gives you critical information to build a healthy family. It will tell an individual if they're a carrier of a serious disease they may pass along to their children if their reproductive partner carries the same disease. If someone is planning to have children, it’s important that they speak to their doctor or a genetic counselor about preconception carrier screening.
View video: A Genetic Counselor on Screening
What does it mean to be a carrier?
A carrier of an "autosomal recessive" genetic condition such as Canavan disease shows no signs of illness. The only way to know if an individual is a carrier of Canavan disease—or other autosomal recessive genetic condition—is to be screened or to have a child born with the disease.
If someone is a carrier—of Canavan disease or any other genetic diseases—they'll want to have their partner screened too. If both they and their partner turn out to be carriers of the same disease, they'll want to work with a genetic counselor to discuss the reproductive options for building the family they want.
If someone has had a child affected by Canavan disease, then they already know they and their partner are both Canavan carriers. For any future pregnancy there is a 25% chance of having another child affected with the disease. However, there are reproductive options that can enable carrier couples to build a healthy family.
View video A Genetic Counselor on Options.
Screening recommendations for persons of specific ancestry or geographic origin
While everyone thinking of have a child should consider genetic carrier screening, there are groups for which specific tests are especially recommended
Anyone of Ashkenazi (German or Eastern European) Jewish ancestry should be screened for Canavan disease and the nearly 60 other diseases currently on the list of diseases which affect persons of Ashkenazi heritage. You can see the complete list at the Jewish Genetic Disease Consortium website.
Individuals of Ashkenazi ancestry should note that screening for one of the diseases on the list, Gaucher disease, may reveal that the individual actually has the disease. For more information visit the Medline Plus article on Gaucher and the Gaucher Foundation.
Note on Tay-Sachs: Previously, the recommendation for Tay-Sachs screening was a combination of DNA and biochemical carrier screening (enzyme analysis), in which a saliva test would be followed up by a blood test. This recommendation has been updated; either a saliva test or a blood test are now equally valid for Tay-Sachs screening. Click here for statement from the National Tay Sachs and Allied Diseases Foundation (NTSAD).
If you are of Sephardic (Mediterranean) or Mizrahi (Persian or Middle Eastern) Jewish ancestry, there are specific genetic concerns based on your family’s origin. You can see a disease list at the Jewish Genetic Disease Consortium website.
Persons of African ancestry should consider screening for sickle cell disease.
Persons of Italian, Greek, Turkish, Middle Eastern, South Asian and African ancestry should consider screening for thalassemia.
If you have a family history of genetic disease
Someone who has any family history of genetic disease, regardless of their ancestry, should also consider screening for the particular disease that runs in their family. Make you sure you talk to your doctor.
Where to go for screening
Most Ob/Gyns can order genetic carrier screening. If this is not an option for you, there are a number of hospital-based and community screening programs around the country. Click here for more information and a list of clinics around the country.
JScreen may be a screening option to consider for those with limited access to a doctor or concern for cost. Their ReproGEN test is designed for prospective parents of any ethnic background. It’s based on an at-home saliva test, which is returned to a lab for analysis. Genetic counseling is included. Testing is coordinated with your doctor. There is generally a three-week turnaround time. (The test is currently $149 if you have insurance, $299 for self-pay.)
Recent Articles from the Professional Societies about Updated Screening Recommendations
"Carrier Screening in the Age of Genomic Medicine" (American College of Obstetricians and Gynecologists) Click here.
"Screening for autosomal recessive and X-linked conditions during pregnancy" (American College of Medical Genetics and Genomics) Click here.
"Expanded Carrier Screening in Reproductive Medicine – Points to Consider" (Joint statment from ACMG, ACOG, NSGC, PQF, SMFM) Click here.
