By Jim Waurin, MS, CG (ASCP) Genomic Services, Quest Diagnostics

April 16, 2019 Insights

With the title “Molecular Structure of Nucleic Acids – A Structure for Deoxyribose Nucleic Acid” published in Nature on April 25, 1953, the era of modern genomics began. This seminal paper by James Watson and Francis Crick gave us an understanding of the unique structure of the molecule known as the blueprint of life; the DNA double helix.  The structure of this molecule with its alternating pattern of nucleotide base pairs, adenine-thymine and guanine-cytosine, determines everything from eye color to diseases such as sickle cell and cystic fibrosis.

However, just knowing the structure of DNA wasn’t enough. Researchers found that DNA was packaged into thread-like structures called chromosomes, and that humans had 46 of these with each chromosome being millions of base pairs long. But what was the sequence of all those nucleotides, and what could that tell us?

Discussions to identify and describe the entire human genome began in 1984. In 1990, The Human Genome Project was launched by the Department of Energy and the National Institutes of Health. The project was so huge it gained international participation; to this day, it is considered the largest-ever international science research collaboration. On April 14, 2003 it was announced that the project was completed with over 3 billion base pairs sequenced and without going over budget ̶ an amazing feat.  On April 25, 2003 this milestone was celebrated as the first DNA Day. It was meant to be a one-time occurrence, but the National Human Genome Research Institute (NHGRI) commemorates it every year with various activities that showcase how genomics has transformed our world.

Exploring the impact of the Human Genome Project on our lives

Disease Carrier Testing

While carrier screening for a select number of genetic diseases such as Tay Sachs or sickle cell disease has been available for decades, most carrier tests were based on measurement of gene products. Advances in genomic information and technologies have enabled screening for many genetic diseases from a single DNA sample. Couples can find out long before conception if they are at increased risk for common inherited disorders, and take steps to minimize that risk.

Prenatal Screening

The use of advanced genomic technologies has provided pregnant women with a new way to screen pregnancies for common birth defects which involve extra chromosomes, such as Down syndrome, also known as Trisomy 21. Initially, maternal age was used as a screening tool for these disorders. Then pregnancy-specific blood biochemical markers were measured to assess risk. Now, thanks to the Human Genome Project, segments of placental DNA circulating in maternal blood are sequenced and aligned to their chromosomal origin in order to determine if there is any extra or missing DNA from several chromosomes. This extremely accurate maternal screen (also known as non-invasive prenatal screening, or NIPS) would not be possible if we did not know the sequence of nucleotides on the chromosomes.

Newborn Testing

While newborn screening helps identify babies at high risk for many treatable disorders, there are some diagnoses which remain a mystery, despite multiple testing platforms. In these cases, the use of whole exome sequencing (WES) has opened a new door to provide parents answers about a child’s symptoms. This technique compares the entire coding sequence of the child to the parents in order to diagnose rare conditions.

Pharmacogenomics

It has been observed for a long time that different individuals have different reactions to the same medication, or no reaction at all. It turns out that there are specific genes involved in metabolizing drugs. By using genomic technologies to look for variants in genes that alter the way a patient metabolizes a drug, providers can better prescribe medications in order to get the best outcome for a patient on initial dosing.

This April 25, take a moment to learn more about DNA, and genetic research, and why it is having such a big impact on healthcare today.

For more information about National DNA Day:  https://www.genome.gov/20519689/celebrate-dna-day-with-nhgri/