Your Resource for all Things Relating to Factor V Leiden

Should my newborn or adolescent child be tested?

Genetics and your family's health

It is important for parents to learn as much as they can about their family health history in order to have a complete record for your child throughout his or her life.


A child gets one set of genes from the father and one set from the mother. These genes can match up in many ways to make different combinations. This is why some family members look a lot alike and others don’t look like each other at all. Genes can also increase the risk in a family for getting certain health conditions. This increase in risk is usually due to a genetic disorder.


A genetic disorder can be caused by a mutation, or a change in your DNA. These mutations can be either inherited, or in other words passed on from parents to their children, or they can be de novo, meaning they occur spontaneously during development.


While many conditions on state newborn screening panels are caused by mutations that occur spontaneously during development, collecting a family health history is still helpful for expecting parents. This history could help identify inherited genetic disorders that are not tested for on the newborn screen.

It is interesting to note that most babies identified with a genetic disorder through newborn screening are from families who were not aware of the genetic disorder or aware of it ever occurring in their family history.  


A family health history allows parents to know what conditions to look out for not only during newborn screening, but also later on as their children grow and develop. Knowing about family health history from the beginning can help you and your child make smart and healthy decisions from the start.

Family Health History Plays a Major Role In:

  • Identifying familial and hereditary disorders
  • Determining inheritance patterns and recurrence risks for known and suspected genetic disorders
  • Identifying those at risk for a genetic disorder
  • Identifying those not at risk for a genetic disorder
  • Providing information necessary for appropriate genetic counseling
  • Providing an important adjunct to patient management of all childhood diseases, such as growth problems and asthma.

Ideally a family history is recorded at your child’s first visit to the pediatrician, as well as a mother’s first prenatal visit. A family history should also be updated yearly with each well-child visit.

Questions Your Pediatrician May Ask About Family History

  • Are there any health problems that are known to run in your family, or that close relatives have been told are genetic? If so, what are these conditions?
  • Is there anyone in the family who had cancer, heart disease, or other adult-onset health problem at an early age, such as between 20 and 50?
  • Does/did anyone in the family have intellectual disability, learning problems, or have to go to a special school?
  • Have there been any early deaths in the family, including stillbirths, infant deaths, multiple miscarriages, or shortened life span?
  • What is your ethnic background? Some genetic conditions are more common in certain geographic, ethnic, and racial groups.​
  • Have any relatives had extreme or unexpected reactions to medications or therapy?

According to a survey by the Centers for Disease Control and Prevention, although 96.3% of Americans considered knowledge of family history important to their personal health, only about 30% have ever tried to actively gather and organize their families’ health histories.

The best family health history will have information from several generations. Begin by recording information about yourself, your parents, siblings, and children. Then move on to aunts, uncles, cousins, and grandparents. Starting a conversation with your relatives is a great place to begin collecting information.

Genes in Life was created by Genetic Alliance, a nonprofit organization founded in 1986 and based in Washington, DC. Genetic Alliance is a health advocacy organization committed to transforming health through genetics and works to connect consumers to the smart services they need to make informed decisions about their health and healthcare. The goal of Genes in Life is to answer your questions about health and genetics. 


For more information on genetics and collecting your family health history and sharing it with your healthcare provider, visit their website at

What is the Recommended Uniform Screening Panel (RUSP)?

The RUSP is a list of disorders that the Secretary of the Department of Health and Human Services (HHS) recommends for states to screen as part of their state universal newborn screening (NBS) programs. You have probably heard it referred to as the “newborn screen”.

Disorders on the RUSP are chosen based on evidence that supports the potential net benefit of screening, the ability of states to screen for the disorder, and the availability of effective treatments. It is recommended that every newborn be screened for all disorders on the RUSP.

Although states ultimately determine what disorders their NBS program will screen for, the RUSP establishes a standardized list of disorders that have been supported by the Advisory Committee on Heritable Disorders in Newborns and Children and recommended by the Secretary of HHS.


What conditions are screened for in my state?

All states require newborn screening for every infant. The number and type of conditions a baby will be screened for vary depending on the state in which he or she is born. Each state public health department decides which conditions are coded on its panel. They also develop and manage each state’s newborn screening program, which is designed to ensure that babies with out-of-range screening results are notified and receive diagnostic testing and follow-up care.

Most states will screen for all or most of the conditions found on the RUSP. Newer or recently discovered conditions go through an adoption process to get added. Some states screen for more conditions.

Baby’s First Test and their website is the nation’s resource center for newborn screening information. This organization provides current educational and family resources about newborn screening at the local, state, and national levels. is supported by the Health Resources and Services Administration (HRSA) of the U.S. Department of Health and Human Services (HHS). There website can be found at


Click on the link below and then click on your state on the map to see what conditions are tested for in your state.

Is Factor V Leiden included on the list of disorders tested for on the RUSP?

Although many of the conditions found on state newborn screening panels are genetic disorders, Factor V Leiden is not currently on the RUSP list or any state list of conditions being tested for as far as we know.

Should My Newborn or Adolescent Child Be Tested?

This question can be a controversial topic depending on the organization you look to for the answer.


The following scenario is becoming more and more commonplace as the public has become increasingly aware of genetics and genetic disorders in recent years…

A father brings his 5-year-old son for a well-child visit. During the appointment, he mentions that the boy’s aunt developed a blood clot at age 26 and was found to be heterozygous for the Factor V Leiden mutation. He asks you if his son should be tested.


Over the past decades, several inherited risk factors for thrombosis (blood clotting) have been identified. Inherited risk factors like Factor V Leiden have gained increasing attention and pediatricians are being asked to consider testing in healthy children who have a family history of thrombosis or thrombophilia.

The American Academy of Pediatrics (AAP) and the American College of Medical Genetics and Genomics (ACMG) state that the genetic testing and genetic screening of children are commonplace with over 4 million infants in the United States every year undergoing newborn screening for metabolic, hematologic, and endocrine abnormalities for which early treatment may prevent or reduce morbidity or mortality.


They go on to state that our knowledge of genetics is growing rapidly as is consumer interest in undergoing genetic testing. Statements about genetic testing of children in the United States written in the past 2 decades need to be updated to consider the ethical issues arising with new technologies and expanded uses of genetic testing and screening. The growing literature on the psychosocial and clinical effects of such testing and screening can help inform us about best practices.

Finally, the American Academy of Pediatrics (AAP) and the American College of Medical Genetics and Genomics (ACMG) state that decisions about whether to offer genetic testing and screening should be driven by the best interest of the child. 


Nevertheless, the usefulness of performing genetic testing on children has been increasingly scrutinized, and it is important to understand the potential benefits and limitations of testing.


Potential benefits of testing for inherited thrombophilia like Factor V Leiden in healthy children

  • Improved counseling for adolescent females considering oral contraceptive pills (OCPs). The baseline annual incidence of venous thrombosis or VTE is about 1 per 12,500 for women of reproductive age and increases to 1 per 3,500 for those on OCPs. For subjects who are heterozygous for the Factor V Leiden mutation and on OCPs, this baseline annual risk is increased 35-fold to approximately 1 per 350 women. The young woman will be better informed regarding her choices and may choose lower-risk alternatives, such as progesterone-only preparations or an intrauterine device.
  • Targeted preventative measures in high-risk situations, e.g., after a femur fracture in an obese teenager who also has Factor V Leiden, or prior to long-distance (> 6 hours) air travel for teenagers.
  • Education about signs and symptoms of a venous blood clot, which could lead to earlier diagnosis.
  • Promotion of lifestyle modifications including avoidance of additional prothrombotic risk factors (sedentary lifestyle, obesity and smoking).
  • Although you will find conflicting studies and more investigation is needed, some research has suggested that Factor V Leiden is associated with ischemic stroke in children and young adults, particularly in patient populations in which there is an increased clinical suspicion of prothrombotic state.

Limitations of testing for inherited thrombophilia like Factor V Leiden in healthy children

  • There is very little opportunity for the testing to benefit a young child. The incidence of venous thrombosis in healthy children is extremely low (0.07/10,000), so that long-term anticoagulation in a healthy child is unwarranted.
  • There are ethical issues of genetic screening in children who may lack the maturity and understanding to make an informed decision, especially when there currently is no demonstrated benefit to testing during childhood.
  • Interpretation of test results — particularly for protein C, protein S, and AT deficiency — can be challenging because normal ranges change throughout early childhood and reliance on adult normal ranges may result in misdiagnosis.
  • If an underlying defect has not been identified in a family member, negative testing may provide a false sense of security.
  • Identification of an inherited thrombophilia like Factor V Leiden may cause unnecessary anxiety.

I believe Factor V Leiden should be added to the newborn screening panel in my state. What can I do?

For a condition to be added to the RUSP, it has to be nominated to the committee by an individual or group. People that have nominated conditions in the past include parent advocates, researchers, or organizations. Once the committee reads the nomination, it is reviewed by workgroups who will then decide if there is enough evidence to support screening for the condition. Following these discussions, the workgroups produce a recommendation, which is reviewed by the Secretary of Health and Human Services. Ultimately, the Secretary of Health and Human Services makes the decision on whether to add the condition to the RUSP. It may take an extended period of time for the committee to review the nominated conditions because it is important to be sure that screening for conditions on the RUSP benefits the most newborns. Once a condition is added to the RUSP, a state may take additional time before screening begins because setting up funding, labs, and educational materials about a new condition is a large task.


For information about nominating a condition, click here.

Final thoughts on Testing Children for Factor V Leiden

Genetic counseling should be utilized both in the decision to get tested and also used in the interpretation of the test results. Genetic counseling can be performed by clinical geneticists, genetic counselors, or any other health care provider with appropriate training and expertise.

For healthy children who have a family history of thrombosis, the decision to perform testing should be made on an individual basis only after counseling the family regarding the potential benefits and limitations.


During the counseling, one should discuss how the results might affect the medical management of the child.

Adolescents, particularly females, are likely to have the most to gain from testing for Factor V Leiden or other inherited thrombophilia.


Ultimately, parents have the option of pursuing additional screening for their child if they are concerned about a specific condition not being screened for in their state.

Deciding whether you or your child should be tested for Factor V Leiden is a personal decision.

The American Factor V Leiden Association is working hard to promote public awareness, provide education and be a resource for knowledge.

Our current program initiative on testing is aimed at improving testing guidelines by taking a common sense approach and looking at all variables related to the disorder.

We hope to publish an in-depth position statement on Factor V Leiden testing in the coming months.

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