Prenatal Diagnostic of Rett Syndrome Proposal - Genetics Presentation Transcript
Prenatal diagnostic of rett syndrome Nicole Colón Carrión
Rettsyndrome 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.
Expectedresults The DNA of the rats containing the mutation will not hybridize while the DNA of the normal rats will.
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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