Remember the Human Genome project? It was the world’s largest collaborative biological project to map all of the genes of the human genome, the biological blueprint or recipe for the creation of a human being. Completed in 2003 after 13 years of intense research carried out in different countries. The information obtained from the project contains around 3,000,000,000 data points for a cost of around $5Bn.
What did we learn?
One of the features of this impressive programme was the identification of the specific genome defects that cause over 2,000 genetic diseases. These diseases include cystic fibrosis, sickle cell anaemia and haemophilia, which are presently incurable. The problem with many of these kinds of genetic diseases is that they are carried on what are called recessive genes. This basically means that the faulty gene hides in the background, usually on the X chromosome and the individual carrying the disease is unaware of it. The mathematics of human genetics tells us that if both partners trying to conceive are found to be carriers of the same defect, or the female is a carrier of an X-linked defect, the couple has a 25% chance of conceiving an affected child.
How likely are you to be a carrier?
A recent study of more than 2,000 people trying to conceive who were screened for 10 types of genetic diseases identified 8.6% of people as carriers. 2.2% of couples when BOTH partners were tested had a chance of passing on the disease to their offspring. The most common genetic diseases identified were cystic fibrosis followed by spinal muscular atrophy and fragile-X syndrome. The study was presented at the recent European Society for Human Reproduction and Embryology (ESHRE) conference. The research was presented by Dr. Marco Fabiani from Igenomix Italia. Dr. Fabiani argued that many couples who are unaware of their carrier status and trying to conceive are at risk of transmitting a genetic disease to their child.
The problem is that testing is expensive, particularly if screening for a number of genetic diseases. Therefore, Dr. Fabiani suggests that extended carrier screening is utlilised. This involves testing for just 10 common diseases as a new cost-efficient alternative to broader population screening. He pointed to his study as an example of the value of extended screening. In the course of the study he managed to detect three at-risk couples who were trying to conceive naturally, highlighting the importance of such knowledge to those couples. In total, the study contributed to the identification of 10 couples at risk of having a baby with a genetic disease.
What’s the cost?
Dr. Fabiani suggested that the future cost of extended screening for around 10 genetic conditions could be anything from $100 to $1,000 per participant. However, given the devastating consequences of these genetic conditions it seems money well spent for peace of mind.