A paper in the New England Journal of Medicine (the world’s premier medical publication) has looked at how genetics may be a factor in how badly the COVID-19 virus can hit you. The authors looked at the recent epidemics in Spain and Italy and focused on people who suffered respiratory failure during the infection (those who needed oxygen, CPAP therapy or mechanical ventilation).
Just under 835 people with COVID-19 who got respiratory failure were identified. They were compared with a ‘control’ group of 1,255 people selected from blood donation or out-patient locations. The controls were seen as representing the general population. All the patients and controls had a very sophisticated genetic analysis performed.
It turned out that, in this study at least, there was indeed a particular sequence of genes on one chromosome that was strongly associated with developing respiratory failure. What was also interesting is that this gene sequence was more commonly seen in people with Blood Group-A. So, might Blood Group-A blood (haemoglobin actually) be a risk factor for having severe disease in those who go down with COVID-19? Well, I don’t think we are there yet, nor it does not explain why in the UK people with South Asian heritage may be over-represented in the ‘severe disease and death from COVID-19’ statistics.
Criticisms of the study? Relatively small numbers of subjects. The link between the gene anomaly and ABO blood groups was not explored in detail. I could not see an analysis or table of data comparing the case and control group subjects. Were they similar or not? Don’t know. The ideal control group subjects should closely match the case subjects (age, gender, co-morbidity, smoking etc. etc). If not it isn’t really possible to say who you are truly comparing the patients to.
I pulled some data from a table in Wikipedia. I throws a bit of a spanner in the Group-A theory works. It does however, reveal quite a difference in blood group types between the populations of various South Asian countries and the UK.
|Blood Group (%)||O||A||B||AB|
|S. Asians combined||30||22||38||12|
(2) Quite why the Bangladesh figures do not add up to 100% is not clear
Quite obviously, there is much more to this story than meets the eye