What does a family health history of cerebral palsy mean for people who are planning for pregnancy?
Most babies are healthy, but about 3-5% have a birth defect or other problem with development. Cerebral palsy (CP) is one of the most common birth defects. Many people planning for pregnancy may have a family member with CP and wonder whether they have a higher chance to have a baby with CP or something similar. Data from genetic testing shows that some people with CP actually have an underlying genetic condition. Collecting family health history and genetic testing may be helpful for some families.
What is cerebral palsy (CP)?
Cerebral palsy is the most common motor problem of childhood. Children with CP have a harder time moving and staying balanced. The degree of movement difficulty varies. On the more severe side, some may need to use a wheelchair. Others may have more mild symptoms, such as walking more awkwardly than others. Some people with CP have other health issues in addition to movement difficulties. Of course, people with CP can live engaging and fulfilling lives and have close relationships with friends and family.
How common is cerebral palsy (CP)?
Cerebral palsy affects about 1 in 300 to 1 in 500 people in the United States.
By comparison, Down syndrome occurs in about 1 in 700 births, heart defects occur in almost 1 in 100, and cleft lip and/or palate happens in about 1 in 2,000 babies. Therefore, many people who are planning for pregnancy may have a family health history of cerebral palsy and wonder whether they have a higher chance to have a child with CP, too.
What causes CP?
The brain controls the ability to move and coordinate muscles in the body. Differences in brain development or brain damage therefore cause cerebral palsy. New medical research on people with CP at birth shows that there are many possible reasons for the damage to the brain that causes CP. This is different from what was often believed in the past. Prior to this new research, CP was commonly believed to be caused by birth trauma, like problems during a baby’s delivery, that limited oxygen supply to the baby’s brain and caused brain damage. In fact, there are likely many different possible causes of the underlying brain problems that cause CP. Some of these are known, like brain infections, brain injuries, or certain blood problems, such as those that might cause a blood clot to form in the brain. Babies born early (premature delivery) also have a higher chance for CP. In addition, new research shows that there are other causes of CP, such as some genetic conditions.
Is cerebral palsy genetic?
New studies on genetic testing of people with CP at birth shows that anywhere from 10% to over 50% may have a genetic condition.
A genetic condition means that the health symptoms of the disease are caused by a person’s DNA. DNA is the blueprint for how a person’s body grows, functions, and develops. DNA is organized into genes. People have two copies of most genes, one from their mothers and one from their fathers. Sometimes there is a difference in the DNA making up a gene compared to most people in the population, called a DNA variant. Some DNA variants may affect how a person’s brain development occurs, leading to cerebral palsy.
What should people with a family health history of cerebral palsy do if they are planning for pregnancy?
The Center for Disease Control (CDC) recommends collecting family health history when planning for pregnancy. People who have a blood family member with CP should ask questions about that family member.
To collect a family health history, here are some questions to ask about the family member with CP:
How is the family member with CP related to the person planning for pregnancy (e.g. father’s half-brother’s son or maternal grandmother’s brother’s daughter)
At what age did the symptoms of CP begin (i.e. Did the symptoms appear right away at birth, and if not, at what age did the first symptoms of CP appear?)
What other health problems has the family member with CP had? (e.g. premature delivery, low birth weight, severe learning problems, seizures, vision or hearing problems, problem with blood clotting, serious infections, serious injuries like from a car accident, etc.)
How old is the family member with CP? If the person is no longer living, how old was he or she when she died and what was the cause of death?
What medical records are available on the person with CP? Is it possible to get permission to access those medical records?
Did the family member with CP ever have an appointment with a genetics specialist (like a medical geneticist) or have genetic testing?
Are there any other family members with birth defects, muscle or nerve problems, or problems with development?
In many cases, some of the details above about a family health history may not be available to the person getting ready for pregnancy. If the person with cerebral palsy is living, it would help for that person to have an appointment with a genetics specialist, called a medical geneticist. A medical geneticist is a physician who has specialized in diseases that are genetic or inherited. A medical geneticist will likely do a physical examination, review the medical records, ask questions about family health history, and may order some genetic testing depending on the particular symptoms and features of CP in that person.
Genetic services and genetic testing for a person with CP may make a definite diagnosis and help guide that person’s care and medical treatment.
It can be uncomfortable when planning for pregnancy to discuss family health history with family members, particularly when it comes to someone in the family with a serious health issue or problem with development. It may be helpful to point out the benefits of seeking genetic services and possibly genetic testing for the person with CP.
If there is a known genetic cause of CP in the family, what does that mean for family members who are planning for pregnancy?
A specific diagnosis through genetic testing helps family members better understand their chances to have a child with cerebral palsy. As mentioned above, some studies have shown that 10% to 50% of people with CP have a genetic cause of their CP. Having a genetic cause of CP may sometimes mean there is a higher chance for other family members to have a child with CP, but in other cases, it will not.
Sometimes the DNA variant in the person with CP is new in that person, in which case, the chances for other family members to have a child with CP will be the same as anyone else in the general population, between 1 in 300 to 1 in 500. Family members may find that information very reassuring when planning for pregnancy, which can be a very anxious time.
Other times, genetic testing may show that a person with CP has an inherited condition. For example, one type of inheritance is called autosomal recessive. In autosomal recessive inheritance, the person with the condition, in this case cerebral palsy, got one DNA variant for the disease from each parent. The parents don’t have CP because they have only one copy of the DNA variant. This is called being a carrier. People with a family health history of CP from a known genetic cause may be able to have carrier testing to find out if they have the DNA variant in the family that causes CP. If they do, their partners may also be able to have carrier testing. If both parents are carriers of the DNA variant, they will have a 1 in 4 chance to have a child with that particular form of CP.
What if the family member with CP is not available for any medical services or genetic testing?
It is common that people who are planning for pregnancy and have a family health history of a problem with development are uncomfortable approaching family members about the condition. In other cases, the family member with CP is no longer living. In those cases, an expert in genetics like a genetic counselor will look at the nature of the relationship between the person planning for pregnancy and the family member with CP and give a sense of whether the chances are much higher than the general population’s chances for CP. In some cases, they may recommend genetic testing for the person planning a pregnancy. However, the more information people can gather about their family health history, including the person with CP, the better.
What if the family member with CP has genetic testing and no DNA variant is found as a cause of the CP?
Genetic testing is not able to identify all causes of CP or even all genetic causes of CP. The science of genetics is still evolving. However, in this case, the people planning for pregnancy have done what they can to determine the cause. They can meet with a genetic counselor to discuss what is known and what their chances are for a child with something similar.
Standard fertility or prenatal care often includes genetic testing. Won’t that address any chances for CP from inherited causes?
No, standard genetic testing offered during pregnancy does not assess risk based on a family health history that includes cerebral palsy. Prenatal care providers and fertility care providers definitely want what is best for their patients. They collect some basic family health history and offer some standard genetic testing. Sometimes, they will refer patients to genetics specialists like genetic counselors. However, they are very busy and it is hard to keep up with the changes in the science of genetics.
If people wait until they are pregnant to collect family health history, they will miss some options that might be beneficial to them.
For example, some people planning for pregnancy with a known family health history of inherited conditions may consider different options for family planning. For example, many people don’t know that in vitro fertilization (IVF) can be used to do genetic testing on embryos even if a couple does not have fertility problems. Other couples may choose to adopt or to use an egg or sperm donor. Others may ultimately decide not to have children.
In addition, waiting until pregnancy will place unnecessary time constraints on collecting the important medical information on a family member with CP. The extra anxiety may be able to be avoided.
Who should people who are planning for pregnancy talk to about their family health history of CP?
Genetics professionals have special training in genetics and have been shown to have more focused training about genetic risks and genetic testing compared to medical professionals in other specialties or primary care. Mainstream Genomics’ Pregnancy Planning Family Screen is a good first step and will take a complete look at family health history, including any family members with cerebral palsy.
Rosenbaum et al. A report: the definition and classification of cerebral palsy April 2006. Dev Med Child Neurol Suppl. 2007 Feb;109:8-14.
Data and Statistics for Cerebral Policy, Center for Disease Control. https://www.cdc.gov/ncbddd/cp/data.html
Christensen, D et al. Prevalence of cerebral palsy, co‐occurring autism spectrum disorders, and motor functioning – Autism and Developmental Disabilities Monitoring Network, USA, 2008. Developmental Medicine and Chid Neurology. 2014, 56(1): 59-65.
Causes and Risk Factors for Cerebral Palsy, Center for Disease Control. Accessed 12/13/2020: https://www.cdc.gov/ncbddd/cp/causes.html
Sastry S and F Millan. “Reexamining the Causes of CP: Why Genetic Testing Should Be Considered. Oral presentation, November 2020, National Society of Genetic Counselors Annual Conference. (Virtual)
Genetic or Other Causation Should Not Change the Clinical Diagnosis of Cerebral Palsy. Journal of Child Neurology. 2019 34(8): 472-476.
Nelson KB, Ellenberg JH. Obstetric complications as risk factors for cerebral palsy or seizure disorders. JAMA. 1984;251(14):1843-1848.
Grether JK, Nelson KB. Maternal infection and cerebral palsy in infants of normal birth weight. JAMA. 1997 Jul 16;278(3):207-11. Erratum in: JAMA 1998 Jan 14;279(2):118.
Torfs CP, van den Berg B, Oechsli FW, Cummins S. Prenatal and perinatal factors in the etiology of cerebral palsy. J Pediatr. 1990;116(4):615-619.
Badawi N, Kurinczuk JJ, Keogh JM, et al. Intrapartum risk factors for newborn encephalopathy: the Western Australian case-control study. BMJ. 1998;317(7172):1554-1558.
McMichael G, Girirajan S, Moreno-De-Luca A, et al. Rare copy number variation in cerebral palsy. Eur J Hum Genet. 2014;22(1):40-45. doi:10.1038/ejhg.2013.93
Oskoui M, Gazzellone MJ, Thiruvahindrapuram B, et al. Clinically relevant copy number variations detected in cerebral palsy. Nat Commun. 2015;6:7949. Published 2015 Aug 3.
Segel R, Ben-Pazi H, Zeligson S, et al. Copy number variations in cryptogenic cerebral palsy. Neurology. 2015;84(16):1660-1668. doi:10.1212/WNL.0000000000001494
McMichael G, Bainbridge MN, Haan E, et al. Whole-exome sequencing points to considerable genetic heterogeneity of cerebral palsy. Mol Psychiatry. 2015;20(2):176-182.
Corbett MA, van Eyk CL, Webber DL, et al. Pathogenic copy number variants that affect gene expression contribute to genomic burden in cerebral palsy [published correction appears in NPJ Genom Med. 2019 May 31;4:11]. NPJ Genom Med. 2018;3:33. Published 2018 Dec 14.
Takezawa Y, Kikuchi A, Haginoya K, et al. Genomic analysis identifies masqueraders of full-term cerebral palsy. Ann Clin Transl Neurol. 2018;5(5):538-551. Published 2018 Mar 26.
Jin SC, Lewis SA, Bakhtiari S, et al. Mutations disrupting neuritogenesis genes confer risk for cerebral palsy. Nat Genet. 2020;52(10):1046-1056.
Moreno-De-Luca A, Ledbetter DH, Martin CL. Genetic insights into the causes and classification of cerebral palsies [published correction appears in Lancet Neurol. 2012 Mar;11(3):208]. Lancet Neurol. 2012;11(3):283-292.
Kruer MC, Jepperson T, Dutta S, et al. Mutations in γ adducin are associated with inherited cerebral palsy. Ann Neurol. 2013;74(6):805-814.
Planning for Pregnancy, Center for Disease Control. Accessed 12/13/2020: https://www.cdc.gov/preconception/planning.html
Data and Statistics on Birth Defects, Center for Disease Control. Accessed 12/13/2020: https://www.cdc.gov/ncbddd/birthdefects/data.html
Data and Statistics on Congenital Heart Disease, Center for Disease Control. Accessed 12/13/2020: https://www.cdc.gov/ncbddd/heartdefects/data.html.
Facts about Cleft Lip and Palate, Center for Disease Control. Accessed 12/13/2020: https://www.cdc.gov/ncbddd/birthdefects/cleftlip.html#:~:text=How%20Many%20Babies%20are%20Born,palate%20in%20the%20United%20States.