PRENATAL DIAGNOSTIC OF RETT
SYNDROME
Nicole Colón Carrión
RETT SYNDROME
Is a disorder of the nervous system that
leads to a regression in development.
Is classified as an X-linked dominant
inheritance disease, which means that it
mostly affects girls.
It affects approximately 1 person per 10,000
Is caused by mutations in the MECP2 gene,
located on chromosome X.
INTRODUCTION
Rett syndrome is not evident at birth, and
occurs primarily during the second year of life.
Infants with this syndrome seem to grow and
develop normally, but then they stop developing.
Doctors clinically diagnose Rett syndrome by
observing signs and symptoms during the
child's early growth and development but at this
time there’s no diagnostic before the syndrome
is visible.
MECP2
MECP2 is a gene that provides instructions
for making its protein product, MECP2.
MECP2 is essential for the normal function of
nerve cells.
The MeCP2 protein is likely to be involved in
turning off ("repressing" or "silencing")
several other genes.
This prevents the genes from making
proteins when they are not needed.
LONG TERM GOAL
This investigation aims to find a prenatal
diagnosis of Rett Syndrome.
The faster you treat the patient, less severe
will be the syndrome.
OBJECTIVES
Verify if a prenatal test for the presence of a
MCP2 gene mutation in a rat model could be
used as a Rett syndrome diagnosis.
HYPOTHESIS
If the sequence of DNA hybridizes the
mutation will not be present. If the DNA does
not hybridize the mutation is present.
METHODOLOGY
Performed in 2 group of 10 pregnant rats.
One group will contain the mutation of the
gene MECP2, while the other will be normal.
First a small sample of cells of the patient, in
this case the mouse is extracted by a
process called Chorionic Villus Sampling.
Then the DNA molecules are replicated by a
process called PCR.
PCR METHOD
The DNA molecules of the amniotic fluid, polymerases, nucleotides and primers of the gene MECP2 are heated to 95°C. This causes the two complementary strands of DNA to separate.
Lowering the temperature to 50°C causes the primers of MECP2 gene to bind to the single-stranded DNA "template". The polymerase attaches and starts copying the template.
The temperature is again increased, this time to
72°C. The polymerases add further
nucleotides to the developing DNA strand and at
the same time, any loose bonds that have
formed between the primers and DNA segments
that are not fully complementary are broken.
After 20 cycles about a million molecules are
cloned from a single segment of double
stranded DNA.
Finally the DNA will be sequenced and then
will be compared by a process called DNA
hybridization.
EXPECTED RESULTS
The DNA of the rats containing the mutation
will not hybridize while the DNA of the normal
rats will.
REFERENCES
Professor Josette Manchini.Rett syndrome .
July 2002.
http://www.orpha.net/data/patho/Pro/en/Rett-
FRenPro91.pdf
Blanco, Natalia. Manresa, Virginia. Mesch,
Gisela. Melgarejo, Mauricio. SINDROME DE
RETT: CRITERIOS DIAGNOSTICOS . January
2006.
National Institute of Child Health and Human
Development. Rett syndrome. April 2006.
Genetic engineering & Biotechnology News.PCR Gains Momentum with New Applications. July 2005. http://www.genengnews.com/gen-articles/pcr-gains-momentum-with-new-applications/993/
Gaston Calfa,1 Alan K. Percy,1,2 and Lucas Pozzo-Miller. ON EXPERIMENTAL MODELS OF RETT SYNDROME BASED ON Mecp2 DYSFUNCTION. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3059199/?tool=pubmed
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