Questions: The Human Genome Project and Genomic Medicine

Question 1

The Human Genome Project had a competitor: Craig Venter's private company Celera Genomics. What was the difference in their approaches, and what was the significance of the competition?

Model answer: The public HGP consortium used a 'clone-by-clone' approach: mapping the genome into ordered chromosomal fragments, sequencing each systematically. Celera used 'whole genome shotgun' sequencing: breaking the genome into millions of random fragments, sequencing them all, and using computers to assemble overlapping reads. The competition accelerated both efforts and led to a joint announcement in 2000 (draft sequence). The race raised questions about whether public goods could be privatized: Venter initially planned to patent and charge for access to sequence data, which the public consortium and its funders opposed. The eventual outcome left the sequence publicly available.

The HGP-Celera competition is a key case study in tensions between public and private science, and the question of who controls fundamental biological data. The public domain outcome was not inevitable — it reflected deliberate policy choices and the Wellcome Trust's insistence on free data access.

Question 2

The human genome was expected to contain 100,000+ genes. The actual count was approximately 20,000-25,000. Why was this surprising, and what did it imply?

• A. It implied that humans were genetically simpler than roundworms
• B. It implied that protein-coding genes alone cannot explain human biological complexity — regulatory sequences, non-coding RNA, and epigenetics must play larger roles than anticipated
• C. It proved that most human genes had evolved very recently
• D. It showed that the genome was mostly composed of viral sequences

Answer: (B)

The C. elegans (roundworm) genome has about 20,000 genes; Drosophila (fruit fly) has about 14,000. Humans having a similar gene count despite incomparably greater biological complexity implied that the complexity lay elsewhere: in how genes are regulated, in alternative splicing of the same gene into multiple proteins, in non-coding RNAs with regulatory functions, and in epigenetic modifications that alter gene expression without changing sequence. The 'gene number surprise' redirected research attention toward regulation and away from simple gene counting.

Question 3

What ethical concerns did the Human Genome Project raise about genetic privacy and discrimination?

Model answer: The HGP's architects recognized that sequencing the human genome would reveal genetic risk factors for disease. This raised concerns: employers might discriminate against workers with genetic predispositions to chronic illness; insurers might deny coverage or raise premiums; individuals might face discrimination based on probabilities rather than actual disease. The Genetic Information Nondiscrimination Act (GINA), passed in the US in 2008, prohibits discrimination in employment and health insurance based on genetic information, but it does not cover life insurance or long-term care insurance. Genetic privacy concerns have grown with consumer genomics and the use of genetic databases in criminal investigation.

The HGP's ethical, legal, and social implications (ELSI) program, which reserved 3-5% of the project's budget for ethical issues, was unusual in proactively funding research on the implications of the science being produced.

Question 4

The completion of the human genome sequence in 2003 has since enabled personalized medicine, making treatment decisions based on individual genetic profiles routine across all of medicine.

• T. True
• F. False

Answer: False

Personalized medicine based on genomics has advanced substantially in specific domains — particularly oncology (tumor genome sequencing guides cancer treatment) and pharmacogenomics (genetic variants predict drug metabolism). However, most clinical medicine remains far from routine genomic personalization. Most common diseases (heart disease, diabetes, depression) are influenced by hundreds of genetic variants of small effect plus environmental factors, making genomic prediction limited. The gap between genomic knowledge and clinical application is large. As of the early 21st century, personalized genomic medicine is a reality in specific niches, not general medical practice.

Question 5

How did the Human Genome Project accelerate DNA sequencing technology, and what happened to sequencing costs after the project was completed?

Model answer: The HGP drove investment in sequencing technology because the project's cost depended on throughput. New sequencing chemistry and capillary electrophoresis reduced costs during the project. After completion, 'next-generation sequencing' technologies (Illumina, 454, Ion Torrent) introduced massively parallel sequencing — millions of DNA fragments sequenced simultaneously — reducing the cost of sequencing a human genome from $3 billion (HGP era) to under $1,000 by 2015, and under $200 by the early 2020s. This cost collapse — faster than Moore's Law in computing — has made genomic research widely accessible and enabled large-scale population genomics studies impossible when the HGP was conducted.