Hemophilia Cured in Mice Models Using New Genome Editing Method

Neha Kamireddi
Source: Health Care Professionals Network
Author: Rachel Lutz
Published: January 5, 2015
Link: http://www.hcplive.com/publications/hemophilia-reports/2014/december2014/Hemophilia-Cured-in-Mice-Models-Using-New-Genome-Editing-Method-

Researchers from Stanford University School of Medicine have been able to cure hemophilia in mice using a new gene editing method. This method is believed to be safer and longer lasting than the current method of gene editing. By inserting a clotting factor gene into the liver cells of the hemophilic mice, the cells were able to produce the clotting factor, curing the mice. This new method does not require nucleases to cut up the DNA, or promoters to activate the inserted gene making it safer than the previous method. The use of nucleases and promoters can cause significant adverse effects so by not using these to insert the clotting factor gene, the mice are safe from new genes inserting themselves randomly in the genome which could lead to cancer. The treatment worked well for both newborn and adult mice. If this method proves to be safe and effective, future studies could lead to a cure for hemophiliacs.

This study connects to our unit on Heredity and our unit on Molecular Genetics. In our unit on Heredity, we learned about hemophilia in the context of recessive alleles. Hemophilia is a disorder caused by deficiency in certain clotting factors. Without these factors, the blood will not be able to clot, causing a minor wound to bleed much longer than a non-hemophiliac. Hemophilia is a recessive sex-linked, X chromosome disorder, meaning that it is passed on through gametes in the X chromosome. For this reason, hemophilia is more likely to appear in men because they only have one X chromosome, so they only need to receive one allele in order to manifest the disorder. This study inserted the clotting factor gene without the need for nucleases and promoters. In our unit on Molecular Genetics, we learned about restriction enzymes (nucleases) and how certain genes are turned on and off. In genetic modification, restriction enzymes are used to cut sections of DNA so that a new section can be inserted. The method mentioned in the article did not require this and instead attaches the new gene to albumin already found in the liver. This was also able to take the place of promoters which would have activated the new gene that was inserted. We learned about promoters in the context of the lac operon gene. The promoter would be where the RNA polymerase would attach in order to activate the inserted gene. By attaching the new clotting factor gene to albumin, there is no need for a promoter to activate the gene. Since this method does not require promoters or nucleases, it is made much safer, and has proven more effective.