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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