Newborn genome sequencing unlocks the blueprint of health

Subject : Science and tech

Section: health

Genetic diseases:

There are 6,000 or so genetic diseases, of which around 3,500 diseases have been documented, and a much smaller number have had their molecular and/or genetic defects mapped.
A significant number of diseases in the population are also treatable but are nevertheless prevalent.
Newborn screening programmes are now in vogue in different countries, and have been deployed in some states in India as well.

Why is it important to sequence newborn genomes?

The rarity of many genetic diseases, the narrow window of opportunity, the long diagnostic paths, and the unfortunate deaths of ill newborns make it very difficult to document and understand these diseases.
However, population-scale genome-sequencing efforts have provided insights into the prevalence of many of these diseases in an unbiased manner.
Discoveries in the last few decades have allowed doctors to diagnose and treat genetic diseases through genomic sequencing in newborns, especially sick newborns.
The whole-genome sequencing could provide a much higher number of positive cases with a diagnosis, around 40%, with 26% of the diagnosed children benefiting from reduced severity of illness due to the rapid diagnosis and, consequently, a significant reduction in the cost of treatments.

Why sequence healthy newborns?

The U.K. National Health Services recently launched a nationwide programme to sequence 100,000 sick newborns.
The BabySeq project funded by the U.S. National Institutes of Health is one of the most comprehensive studies to evaluate the sequencing of newborns for routine newborn care.
One study found that just over 10% of infants had an unanticipated risk of genetic diseases.
When these infants were followed up for three to five years, sequences revealed the causes of disease in three infants; in the remaining 14, a better picture of the risk made way for better medical surveillance.
The sequencing also warranted additional at-risk family members of 13 infants to have their genes sequenced. Three of them benefited from subsequent surgeries.

Challenges:

Newborn whole genome sequencing presents multiple ethical challenges.
- The issue of disclosing and managing incidental and secondary findings raises concerns about privacy and the psychological impact on families.
- The equitable distribution of benefits and burdens associated with accessing and utilising this technology also invokes issues of justice and fairness.

What is a genome?

The genome is the entire set of DNA instructions found in a cell. In humans, the genome consists of 23 pairs of chromosomes located in the cell’s nucleus, as well as a small chromosome in the cell’s mitochondria.
A genome contains all the information needed for an individual to develop and function.
All of the DNA of an organism is called its genome. Some genomes are incredibly small, such as those found in viruses and bacteria, whereas other genomes can be almost unexplainably large, such as those found in some plants.
- The human genome contains about 3 billion nucleotides.
- The rare Japanese flower called Paris japonica has a genome size of roughly 150 billion nucleotides, making it 50 times the size of the human genome.

Genome vs gene

A gene is a part of the DNA while a genome is the total DNA in a cell.
Gene is the hereditary element of genetic information while the genome is the complete set of nuclear DNA.
Gene encodes protein synthesis, whereas genome encodes both protein and regulatory elements of protein synthesis.
The length of the gene is about a few hundred bases while the genome of a higher organism has about a billion base pairs.
Variations in genes are naturally selected, while horizontal gene transfer and duplication cause variations in the genome.

What is whole genome sequencing (WGS)?

All organisms (microorganisms, plants, mammals) have a unique genetic code, or genome, that is composed of nucleotide bases– adenine, thymine, cytosine, guanine (A, T, C, and G).
If you know the sequence of the bases in an organism, you have identified its unique DNA fingerprint or pattern, and determining the order of bases is called sequencing.
Whole genome sequencing is a laboratory procedure that determines the order of bases in the genome of an organism at a single time.
This includes sequencing all of an organism’s chromosomal DNA as well as DNA contained in the mitochondria and, for plants, in the chloroplast.
Whole genome sequencing should not be confused with DNA profiling, which only establishes the probability that genetic material originated from a specific person or group and does not provide details on genetic relationships, the origin of the genetic material, or a person’s susceptibility to particular diseases.
Whole genome sequencing has primarily been utilized as a tool for research, but it was first made available to clinics in 2014.
Whole genome sequence data may be a crucial tool in the future of personalized medicine to direct therapeutic intervention.