CRISPR-Cas9 Current Affairs

Scientists successfully use CRISPR to fix a genetic mutation causing Hypertrophic Cardiomyopathy disease

Scientists for the first time have successfully repaired a genetic mutation in human embryos by using a gene-editing tool called CRISPR-Cas9.

It has freed embryos of faulty DNA that causes deadly hereditary heart disease. It potentially opens the door to preventing 10,000 disorders that are passed down the generations.

Key Facts

Using CRISPR-Cas9 gene-editing technology, scientists were able to repair mutation in the MYBPC3 gene which causes a common heart condition called hypertrophic cardiomyopathy, which is marked by thickening of the heart muscle.

Hypertrophic cardiomyopathy is an inherited cardiac disease and the presence of even one copy of the defective gene can cause symptoms, which usually manifest as heart failure. There is currently no cure for the condition. The correction of the mutation in the embryo using CRISPR-Cas9 has ensured that the child is born healthy and the defective MYBPC3 gene is not passed on to future generations.

How it was achieved?

The CRISPR-Cas9 gene-editing tool was used to remove the genetic mutation and introduce healthy gene in sperm of man with hypertrophic cardiomyopathy. This sperm was later fertilised with eggs from 12 healthy women. It was found that 42 out of the 58 fertilised embryos did not carry the mutation. The remaining 16 embryos had unwanted additions or deletions of DNA. It showed that probability of inheriting the healthy gene increased from 50 to 72.4%.

CRISPR-Cas9 gene-editing technology

Using CRISPR system, scientists can remove, add or alter specific DNA sequences in the genome of higher organisms. It has two components, a single-guide RNA (sgRNA) that contains a sequence that can bind to DNA, and Cas9 enzyme which acts as a molecular scissor that can cut specific DNA sequence. In order to selectively edit a desired sequence in DNA, the sgRNA is designed to find and bind to the target.

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Scientists for first time edit genes of human embryos

Scientists from Oregon Health and Science University, US for first time have successfully edited genes of human embryos to correct defective DNA that cause inherited diseases.

They had used the CRISPR-Cas9 genome editing technology to alter human DNA in single-cell embryos, which allows specific sections of DNA to be altered or replaced.

Key Facts

In this experiment, scientists had used sperm donated from men who carried inherited disease mutations to demonstrate that the genes can be corrected. The one-celled embryos were created in the experiment, were never intended to be implanted into a womb and were only allowed to develop for a few days.

They had used a process called “germline engineering” in which genetically modified organisms pass changes to their offspring to eradicate inherited disease. It allowed so-called permanent germline changes to pass down to any offspring.

The research holds great potential to avoid many genetic diseases, but has raised fears of “designer babies”. It is also considered as a milestone in journey for giving birth to the first genetically modified humans.

CRISPR-Cas9 genome editing technology

CRISPR short form of clustered regularly interspaced short palindromic repeats. It allows scientists to selectively edit genome parts and replace them with new DNA stretches. CRISPR is a collection of DNA sequences that direct Cas9 where to cut and paste. Cas9 is an enzyme that can edit DNA, allowing the alteration of genetic patterns by genome modification. CRISPR-Cas9 technology has the potential to revolutionise the treatment of blood diseases, tumours and other genetic diseases.

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