Telomeres, Telomerase and The Graduate Student

By Amy Price PhD
Carol Greider was still a graduate student when she started work on a project that along with Elizabeth Blackburn and Jack Szostak  won this year's Nobel prize for medicine. These US-based researchers  discovered how the body protects the chromosomes housing vital genetic code.

Genetics intrigue me because they are beautifully ordered and I have wondered and asked how the telomeres and telemorase are sequenced. When the telemeres are shortened life span is reduced whereas if there is uncontrolled growth cell corruption occurs. These scientists did more than ask they worked together to find answers.

Elizabeth Blackburn, of the University of California, San Francisco, and Jack Szostak, of Harvard Medical School, discovered that a unique DNA sequence in the telomeres protects the chromosomes from degradation.


Joined by Johns Hopkins University's Carol Greider, then a graduate student, Blackburn started to investigate how the teleomeres themselves were made and the pair went on to discover telomerase - the enzyme that enables DNA polymerases to copy the entire length of the chromosome without missing the very end portion.

Some inherited diseases are now known to be caused by telomerase defects, including certain forms of anaemia in which there is insufficient cell divisions in the stem cells of the bone marrow. Apparently elevated telomerase can be a biological marker for malignancy and there is research underway to see if vaccines can be developed to arrest the defects.

The Nobel Assembly at Sweden's Karolinska Institute, which awarded the prize, said: "The discoveries... have added a new dimension to our understanding of the cell, shed light on disease mechanisms, and stimulated the development of potential new therapies."

Disease and Genomic Advances

By Amy Price PhD

Until recently only a geneticist Francis Crick and one other individual have had their genome read. Apparently Dr Crick did not wish to know if he had a specific dominant gene for dementia but was happy to know all other variants. No one knows the public impact in the face of fullscale  genetic information and there are ethical concerns as genetic engineering has not enjoyed a widespread safety or success rate but it appears the tide may be shifting.

A 5 month old male baby from Turkey was critically ill. Scientists and doctors teamed together from multiple nations to enable the reading of  his genome quickly and were able to work out that he had a wrong diagnosis. This was reported in 'Proceedings of the National Academy of Sciences'. The analysis only took ten days and determined that the boy suffered a genetic mutation that coded for a gut disease that eventually destroys other organs including the kidneys. Additional clinical tests determined that the boy had the rare disease and he is now recovering.

The boy's physician sent a blood sample and Dr Lifton of Yale Medical school along with teams in Beirut and Turkey decoded the DNA to reveal a diagnosis. The scientists did a follow up study with 39 patients who had the same condition the boy was originally thought to have and found that five them had the same genetic mutation. For practical reasons, the initial concentration is on the small percentage of the genome which codes for proteins rather than the non coding DNA.

Rather than the usual method of  looking one gene at a time hoping to guess which was the right gene causing the problems,  a new method was utilized where they could look at all the genes in the genome simultaneously.  They identified a specific allele which had mutations on both copies and which causes the sufferers not to be able to absorb water or electrolytes through the gastrointestinal tract.

This is a turning point in personalized predictive medicine. Professor Mike McCarthy, a geneticist at Oxford University commented, "This is an interesting study - lots of groups are now using the power of new methods for sequencing the human genome to find DNA changes that underlie rare diseases (and increasingly for common diseases too)".

There is tremendous potential for Genomics to pave the way for diagnostic breakthroughs.