Cerebral palsy (CP) |
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Cerebral palsy is characterized by damage to the motor components of the central nervous system
(brain damage), and it manifests as muscle weakness or spastic muscle paralysis (rigidity of muscles).
In most cases, CP is defined as damage to brain tissue that occurs in the perinatal period, due to
environmental rather than genetic causes.
A number of neurological diseases are caused by hereditary metabolic disorders (inborn errors of
metabolism).
Here involvement of the nervous system tissue can result in a clinical picture that is similar to
that occurring in classical cerebral palsy.
It is important to differentiate between the metabolic disorders and classical CP that occurs as
a result of environmental damage, even though this may not always be possible.
In most cases, the cause is unknown.
Only in a few cases is there a clear history of disruption of the oxygen supply to the fetus
before or during birth, or of another external cause that can explain brain damage, such as
an infection or brain hemorrhage.
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Clinical signs |
The increase in the number of very small premature infants has resulted in an increase in the
number of babies with CP in recent years.
Some already have neurological signs in the first month of life, but in most cases the condition
is only detected during the first year when the infant fails to develop motor skills commensurate
with his or her age. Later, the muscle weakness and rigidity can be discerned.
Tendon reflexes are increased.
Usually the condition does not progress, and improves with physiotherapy.
In about 50% of cases there is mental retardation
in addition to motor problems.
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There are a number of genetic diseases whose clinical manifestations are
similar to those of CP.
These constitute about 10% of the cases of children with a clinical picture of muscle
weakness and rigidity.
The risk that the child has a hereditary, genetic type of CP is increased in the following
cases: absence of an environmental factor indicating acquired damage, progression and
deterioration of the neurological damage over time, the presence of involuntary dystonic
movements, the presence of mental retardation that is more severe than the motor problems,
the absence of signs indicating environmental damage in brain scans (CT or MRI), or the
presence of signs indicating a genetic disease in an examination of the child or in laboratory
and/or imaging tests.
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Cerebral hypertension secondary to hydrocephalus and also
chromosome disorders must be ruled out.
It is especially important to test for metabolic disorders such as leukodystrophy.
All these conditions must be considered by the geneticist.
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Inheritance pattern |
Most cases of CP are not genetically transmitted.
However, in the approximately 10% of cases that are due to genetic causes rather than environmental,
there may be recurrence in future children of the couple.
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Penetrance |
In the metabolic disorders, this varies according to the specific disease.
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Associated features that can be demonstrated by imagery |
Usually there are no defects that can be identified by ultrasound examination during pregnancy.
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What is the risk of recurrence in a subsequent pregnancy? |
The incidence of classical CP is 1 in 350 births.
The risk that siblings will also be affected is low, but according to a number of studies,
in certain types of CP, such as those with dystonic movements and instability, or those with signs
indicative of a metabolic disorder, there is a risk of recurrence of up to 10%.
If there are 2 siblings with the condition, a metabolic disorder must be suspected.
Since these are usually transmitted by autosomal recessive inheritance, the risk that the parents
of an affected child will have another affected child is 25% in every pregnancy.
More distant relatives do not have a significantly increased risk of having a child with this
condition - as noted, the frequency in the general population is up to 1% depending on the
definition used.
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Cerebral palsy
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Molecular genetic information |
The gene for the disease
Only in the genetic cases, depending on the specific condition.
The location of possible genes
Depends on the specific condition.
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Genetic testing |
Diagnostic testing
Tests for specific genetic syndromes should be carried out, and also a blood test to check for
chromosome disorders.
Definitive tests for specific metabolic diseases may be recommended according to the clinical
findings and the decision of the geneticist.
Carrier testing
This usually cannot be performed unless the child has a specific syndrome.
See above under "Diagnostic testing".
Fetal testing
This usually cannot be performed unless the child has a specific syndrome. See above under
"Diagnostic testing".
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