We have crossed an important milestone in the history
of genetic manipulation – and the game changer is the gene editing tool
called CRISPR. Scientists from Oregan have published a paper in Nature
in which they edited an abnormal gene in eggs which were to be fertilzed
resulting in healthy embryos. They edited the MYBPC3 mutation which is
associated with hypertrophic cardiomyopathy of several embryos. On
checking the edited embryos, there were no apparent errors on genome
sequencing. Even cell mosaicism that had been reported in previous
endeavors was almost entirely absent.
How does the CRISPR technique work? Simply put, a
target mutation is identified by a guide RNA. Then the Cas9 enzyme
attaches to the identified DNA, and slices it. Natural cell mechanisms
are used to repair the spliced DNA. In the study from Oregon, scientists
injected the CRISPR gene editing components with the sperm before
fertilization. This led to significant decrease in mosaicism.
Currently there is no FDA approval for germ line
editing in actual human pregnancies. But the technique looks promising.
The ethics, unforeseeable problems which could arise from tinkering with
genes, and formidable costs are some of the barriers to the new
technology. This is nascent science, powerful science but should not
turn out to be deadly science. (Nature 2 August 2017, Scientific
American 2 August 2017)
Guidelines for Newborn Eye Screening
"Pediatricians are the first line of defence in the
newborns world" – states the newly released guidelines for newborn eye
screening by the Ministry of Health and Family Welfare. The prevalence
of blindness in India is 6.5/10,000 children, of which 50% are
preventable. The top three causes are cataract, retinopathy of
prematurity (ROP) and vitamin A deficiency.
The guideline for newborn eye screening includes a
pictorial tool for pediatricians to be able to identify important eye
problems presenting in the neonate. This includes a systematic eye
examination of all newborns, including steps of the red reflex testing.
Pediatricians are recommended to use an ophthalmoscope at a distance of
18 inches to view the fundus individually and simultaneously. Absence of
a symmetric red reflex needs further evaluation by an ophthalmologist.
ROP screening has been recommended for all babies
born less than 2 Kg or below 34 weeks of gestations. Babies born between
34-36 weeks with other risk factors such as ventilation or prolonged
oxygen requirement are also to be screened. Screening must be done at 4
weeks after birth. Babies born at less than 28 weeks gestation must be
screened at 2-3 weeks after birth. Screening must be repeated every two
weeks till ROP regresses or vascularization is complete. Indications for
laser, cryotherapy and intravitreal avastin have also been laid down. (http://nhm.gov.in/images/pdf/programmes/RBSK/Resource_Documents/Revised_ROP_Guidelines-Web_Optimized.pdf)
The Blue Whale Challenge
A deadly online game is urging children round the
world to take their own lives. The game was created by 22-year-old
Philipp Budeikin, a Russian who is currently spending 3 years in a
Siberian jail. The online game is targeting young children urging them
to do a series of dangerous tasks which culminate in trying to take
one’s own life. The tasks range from climbing a crane, carving a
specific phrase on the person’s own hand or arm, doing secret tasks,
poking a needle in the arm or leg, standing on a bridge and roof,
listening to music, and watching videos sent to the challengers by the
administrator.
A 14-year-old boy from Mumbai who was addicted to the
game took his own life by jumping from a multi-storeyed building.
Another 14-year-old from Bengal committed suicide by hanging himself.
Two children on their way to attempting suicide, one in Indore and one
in Solapur, were rescued in the nick of time. In Kerala, there have been
2000 downloads of the game, and the Chief Minister has asked for the
game to be banned.
Parents need to be aware of the deadly repercussions
of online games and their violent content. Children are easy targets for
the cyber brainwashing. (The Times of India 12 August 2017)
Redefining the ‘P’ Value
Is the currently used cut-off of 0.05 to define a
statistically significant ‘P’ value really good enough?
Apparently not! A group of 72 influential scientists have published a
provocative paper explaining why they think it’s not. There is
increasing doubt on the credibility of various new discoveries. The
authors feel that associating "statistically significant" findings with
P<0.05 results in a high rate of false positives even in the
absence of other experimental, procedural and reporting problems.
They propose, that for fields where the threshold for
defining statistical significance for new discoveries is P<0.05,
it should be changed to P<0.005. This simple step would
immediately improve the reproducibility of scientific research in many
fields.
A problem with this suggestion is that there could be
many false negatives. The authors propose this could be circumvented by
increasing sample sizes. However, the increase in sample size would be
of the order of 70% which is difficult for many small researchers.
In many areas of science, the levels for ‘P’ value are much
lower. For example, in particle physics the cut-off is <0.0000003. In
genetics, for more than a decade it has been 0.00000005. Others have
discarded the ‘P’ value in favor of Bayesian statistics. Ronald
Fisher understood that the choice of 0.05 was arbitrary when he
introduced it. Since then, theory and empirical evidence have
demonstrated that a lower threshold is needed. In the search for truth,
maybe it’s time to raise the bar. (Nature 26 July 2017)