What we say

300000000000000 base pairs later…

Roland Barter

December 14, 2018

Personalised, precision, stratified, whatever you call tailored healthcare it has been a key point of discussion now for many years. There is undoubtedly a slow but definite shift towards this type of healthcare and a huge milestone was reached last week. Genomics England announced it had sequenced its 100,000th individual genome and had therefore completed the 100,000 genome project1.

Launched in 2012, the project involved mapping for each participant the 3 billion DNA base pairs which make up the 23 chromosomes in the nucleus of every cell of the human body2. Genomics England embarked on the project hoping to establish a widespread diagnostic tool which could be used to accurately diagnose people suffering from genetic disorders.


The project recruited about 70,000 rare disease patients to have their genome sequenced through NHS Genomic Medicine Centres. Rare diseases are often a result of genetic mutations producing dysfunctional proteins and causing imbalances in the body. These imbalances present themselves as symptoms, however it is not always clear that they are being caused by a mutation in the DNA sequence and they can be attributed to many other causes, potentially leading to a misdiagnosis.


The aim of the 100,000 Genome Project was to gather and use large amounts of genetic data from rare disease patients to identify genetic markers which can provide a definitive molecular diagnosis. The results proved hugely successful, 1 in 4 of the participants with a rare disease received a diagnosis for the first time4.


The power of this type of diagnostic tool is evident from Tilly Young’s story, a 6 year old girl who was suffering from delayed development and seizures but the cause was unknown. Along with her parents, she had her genome sequenced and as a result she was diagnosed with guanidinoacetate methyltransferase (GAMT) deficiency.

Tilly Young


GAMT deficiency is caused by a mutation in the GAMT gene which codes for guanidinoacetate methyltransferase, an enzyme vital in the synthesis of creatine which is crucial for storing energy. A deficit in energy stores impacts organs requiring high levels of energy, such as the brain and muscles, which results in significant complications5. On the bright side, it is treatable and since the diagnosis Tilly’s condition has improved significantly. However it is thought that if an earlier diagnosis had been possible some long-term damage could have been prevented.


Personalised medicine took a massive step forward in 2003 with the completion of the Human Genome Project and this now feels like another momentous milestone has been reached. We are finally able to start using the information we have learned from research to improve the lives of patients who were so hard to treat previously.


  1. https://www.genomicsengland.co.uk/the-100000-genomes-project-by-numbers/
  2. https://www.genome.gov/11006943/human-genome-project-completion-frequently-asked-questions/
  3. https://www.genomicsengland.co.uk/the-journey-to-100000-genomes/
  4. http://www.pmlive.com/pharma_news/genomics_england_reaches_100,000th_genome_sequencing_milestone_1272068
  5. Sylvia Stockler, et al. Guanidinoacetate Methyltransferase Deficiency: The First Inborn Error of Creatine Metabolism in Man. American Journal of Human Genetics. May 1996; 58(5):914-22.