What Is Rett Syndrome (RS)? Rett syndrome is a genetic developmental disorder that almost always affects
girls, but is rarely seen in boys. Rett Syndrome effects 1 in 15,000 little girls. It was identified by Dr. Andreas Rett, an
Austrian doctor who first described it in an article in 1966. It was recognized
as a disorder in 1983, when a second article was published. Children with Rett syndrome
can display a wider range of disabilities that range from mild to severe. The
progression and severity of the disorder depends on a variety of genetic
MECP2 Gene Mutation: Rett Syndrome is caused by
mutations on the X chromosome on a gene called MECP2.
Researchers identified the MECP2 gene in 1999. It is one of the
genes responsible for making a protein needed for normal brain development.
The MECP2 gene makes a protein that is necessary for
the normal development of the nervous system, especially the brain. Rett syndrome affects areas of brain function that are responsible
for cognitive, movement, sensory, emotional, motor and autonomic function.
These, in turn, can have an impact on learning, speech, sensory sensations,
mood, breathing, cardiac function, as well as chewing, swallowing and
syndrome affects areas of brain function that are responsible for cognitive,
movement, sensory, emotional, motor and autonomic function. Thesehave an impact on learning, speech, sensory sensations, mood, breathing, cardiac
function, as well as chewing, swallowing and digestion.
Girls havetwo X
chromosomes in each cell but one of the X chromosomes is inactivated and one
remains active. Depending on the randomly determined balance of which X
chromosome is inactivated (the one with OR without the MECP2 mutation) the
severity of the girls condition may vary.
Two girls who are the
same age and have the same mutation can have very different disabilities.
Boys only have one X chromosome, with the other being the Y chromosome.
In boys, if they have a full MECP2 mutation it is active in all cells resulting
in early miscarriage or a severe clinical picture.
There are children who
have signs and symptoms of Rett Syndrome who do not have this genetic mutation
and others who have a different genetic mutation.
Rett syndrome is a genetic
disorder but less than 5% of recorded cases are inherited or passed from
one generation to the next.
How Rett syndrome manifests itself and progresses
varies from child to child.
Slow Head Growth: Rett syndrome should be
considered when slowing of head growth is observed after birth.
Blood Tests: These
tests are able to confirm the syndrome in up to 80 percent of all
cases. Blood tests will to identify the mutation of the MECP2 gene. Since
the MECP2 mutation can also be found with other disorders, this finding
alone is not enough to make a conclusive diagnosis of Rett syndrome.
Some children with Rett syndrome do not have the MECP2 mutation and may be
diagnosed with classical or variant Rett syndrome based upon meeting
the specific diagnostic criteria
above and testing for other genetic changes may be recommended in some.
Variant forms of Rett often have more preserved speech and/or motor
abilities. There are also variant forms with congenital onset, infantile
seizures and with late onset of regression at preschool or school age.
Molecular Testing: A
formal iagnosis requires either a molecular diagnosis of the mutation (a
Signs and Symptoms: Observable signs and symptoms
need to be present for a diagnosis.
There are specific diagnostic
criteria for typical/classical and for atypical/variant Rett syndrome:
Both forms require that the child
have had a period of regression in developmental skills followed by
stabilization and/or improvements.
A case of classical Rett Syndrome will have all of the main
criteria while those with atypical Rett Syndromemay only have some.
If the diagnosis of Rett syndrome is suspected, a
blood test looking for the mutation on the X chromosome of the gene called
MECP2 should be obtained.
Children who do not have the MECP2 mutation may be
diagnosed with classical or variant Rett syndrome, based upon meeting the
specific diagnostic criteria and testing for other genetic changes.
Variant forms of Rett Syndrome often have more preserved
speech and/or motor abilities.
There are also variant forms with congenital
onset, infantile seizures and with late onset of regression at preschool or
The following exclude a diagnosis of classical Rett but
may be present in atypical Rett syndrome:
Brain injury due to trauma
Severe infection causing neurologic problems or grossly
abnormal development in the first 6 months of life.