Analysis: How Human Genome Sequencing is Creating a Brighter Future for Sick Children

Every week, five new rare diseases are being discovered.

As of now, there are around 8,000 existing disorders in which fewer than five out of 10,000 people share the same condition. While roughly 80% of all rare disorders are genetically based, genome-sequencing technology was never sufficient enough to determine the cause of the disorder, it was only able to sequence a small part of the genome in order to detect any mutations.

Recent advances in technology have lead to the ability to sequence one’s entire genome (and in an affordable way). By discovering the precise genome sequences that code for tumor growth, doctors are now able to provide more exact treatments for patients.

Genome sequencing will be able to help those with developmental disorders as well, and further research will allow for advancements with diseases such as early-onset dementia and multiple sclerosis.

Previously, a technique known as karyotyping was often used, which sorts pairs of homologous chromosomes by their length, allowing one to detect mutations in their base pairs. But the resolution of karyotyping technology only allowed researchers to see large abnormalities. The most recent technology has improved so greatly that researchers believe they can now treat a significantly larger number of patients than ever before.

It is for this reason that Helen Firth, a clinical geneticist at Cambridge University Hospital, and Matthew Hurles, head of Human Genetics at Wellcome Sanger Institute in the UK, have partnered with NHS Genetic Services as well as other prominent groups, to recruit over 12,000 British children and adults with undiagnosed developmental disorders for their Deciphering Developmental Disorders study. In their study, they sequenced the DNA of all participants, as well as the DNA of their parents, paying special attention to “de novo” mutations – those that occurred via egg or sperm production or during the very early stages of the embryo.

Their research has helped numerous patients, such as Evie Walker, an 8-year-old girl who at two couldn’t hold her head up, stand, or walk, and – to this day – is still unable to talk. Going years without answers, the Walkers were finally called to participate in the DDD study, providing a saliva sample that allowed researchers to sequence 20,000 of Evie’s genes to test for commonly inherited developmental disorders. When the results were inconclusive, they turned to the “de novo” mutations – and found that Evie had a series of mutations within the PURA gene, which has been found to play an important role in normal brain development.

Because of Evie’s diagnosis, Sarah Anderson was able to be diagnosed with the same disorder as well. Her family met up with seven others following her diagnosis and formed the PURA Syndrome Foundation – where Evie and Sarah would meet at its first conference in 2016. Unfortunately, the DDD is no longer accepting participants into its study, but research (with proper funding) is expected to continue until 2021.

But this October, NHS England will launch its Genomic Medicine Service – which will provide whole genome sequencing to people with undiagnosed rare diseases and cancer.

For people who have spent their whole life searching for answers, the future is finally looking bright.