What :

• Congenital eye defect
• Size of the eye lens is smaller than normal
• Leads to second-stage glaucoma in children if untreated

Prevalence rate :

• Described in different ethnic groups since 1901
• Mostly in Asia and North Africa
• 2% out of 5.6 million Indian children presenting for lens abnormalities annually have the above disorder

What is in news : Breakthrough work by researchers at the Indian Institute of Science (IISc) here has now resulted in the discovery of yet another mutant gene, WRD8 gene  which has been linked to the development of MSP in two known cases in Karnataka.

How was the study done:

• Genome sequencing of affected children was done
• Using zebrafish as a model system, and Crispr-Cas9 technology to “knockout” and “knockdown” genes in the fish, the scientists identified that mutation in the WRD8 gene
• The scientists then made humanised fish, where the human counterpart of the WDR8 gene (normal and mutated gene sequence) was expressed in zebrafish to show that the gene was indeed responsible for producing the relevant “phenotype”
• Phenotype is a description of a person’s physical characteristics, like eye colour and height.

MAHITI FOR PRELIMS

CRISPR-CAS9

• CRISPR- Clustered Regularly Interspaced Short Palindromic Repeats
• Developed in – 2012
• The method locates the specific area in the genetic sequence which has been diagnosed to be the cause of the problem, cuts it out, and replaces it with a new and correct sequence that no longer causes the problem

CAS-9 (CRISPR-associated protein 9) is an enzyme. It uses a synthetic guide RNA to introduce a double strand break at a specific location within a strand of DNA. It is a system used by bacterial cells to recognize and destroy viral DNA as a form of adaptive immunity.