Cerebral palsy is a group of disorders affecting a person’s ability to move and maintain balance and posture, and it is the most common motor disability in childhood. While once believed to stem primarily from complications during birth like a lack of oxygen, modern research reveals a more complex picture. Genetic factors can play a direct role in many cases, and the causes are varied, involving events before, during, or after birth.
The Role of Genetics in Cerebral Palsy
Genetic mutations are a recognized cause in a portion of cerebral palsy cases, with some studies suggesting they account for up to a quarter of diagnoses. These genetic differences can interfere with brain development and function. Inherited mutations are passed down from parents to children, which may explain why, in rare instances, cerebral palsy appears more than once in a family.
More commonly, the condition is linked to de novo mutations, which are new genetic changes that occur in the child but are not present in the parents’ DNA. These spontaneous mutations can happen in genes for brain development, affecting how nerve cells form, connect, and communicate. Advanced paternal age is associated with a higher rate of these mutations.
Researchers have identified specific genes where alterations can result in a condition that presents as cerebral palsy. These genes are often involved in structuring the brain or ensuring its cells receive the energy needed to function. The identification of these genetic links is shifting the understanding of cerebral palsy from being viewed only as an injury to a condition that can also have a biological foundation.
Acquired and Congenital Causes
Beyond genetics, the causes of cerebral palsy are broadly categorized based on when the brain injury occurs. Congenital cerebral palsy results from brain damage that happens before or during birth, accounting for the vast majority of cases. This can be triggered by various factors, including infections in the mother, such as rubella or cytomegalovirus, that can cross the placenta and affect the developing fetus.
Another congenital cause is severe jaundice in the newborn. If left untreated, high levels of bilirubin can be toxic to brain cells, leading to a form of brain damage called kernicterus. Complications during labor and delivery, such as the umbilical cord becoming compressed or the placenta detaching prematurely, can deprive the infant’s brain of oxygen, a condition known as asphyxia.
Acquired cerebral palsy stems from brain damage that occurs more than 28 days after birth, representing about 10% of all cases. This brain damage can be the result of infections that affect the brain directly, like meningitis or encephalitis. A traumatic head injury, from a fall or car accident, can also cause irreversible damage to the developing brain.
Understanding Risk Factors
A risk factor does not cause cerebral palsy on its own, but its presence increases the likelihood that a child may develop the condition. The most significant risk factors are premature birth and low birthweight. Infants born before 37 weeks have not had the full term to develop, and their brains are more fragile and susceptible to injury, including bleeding or damage to the white matter.
Babies born with a low birthweight, whether premature or full-term, are also at a higher risk. This may be due to slow or restricted growth in the womb, which can be a sign of underlying issues that also affect brain development. A much larger percentage of children with cerebral palsy were born with a low birthweight compared to the general population.
Other circumstances can also elevate the risk. Multiple births, such as twins or triplets, increase the probability, partly because they are often associated with premature birth and low birthweight. Certain health conditions in the mother, including thyroid problems or pre-eclampsia, can also contribute to the risk profile. These factors create a state of vulnerability where the developing brain is more easily damaged.
Genetic Counseling and Testing
For families affected by cerebral palsy, genetic counseling can provide valuable information, especially when the cause is not clear or if there are concerns about future pregnancies. A genetic counselor can help families understand the interplay of genetic and environmental factors. They can review the family’s medical history to assess the possibility of an inherited condition and discuss the implications of genetic testing.
Genetic testing, such as chromosomal microarray analysis or whole exome sequencing, can sometimes identify a specific genetic cause. A microarray looks for small extra or missing pieces of chromosomes, while exome sequencing reads the protein-coding regions of thousands of genes at once to find mutations. Identifying a specific genetic variant can confirm a diagnosis and help doctors anticipate other potential health issues associated with that gene.
Finding a genetic cause can provide families with a definitive answer, which is helpful for emotional clarity and future planning. It helps clarify that the condition was not the result of an event during pregnancy or birth. This knowledge allows for more informed family planning and connects families to specific research and support communities. While testing can provide a diagnosis, it does not currently offer a cure.