Juliet Samuel, Telegraph, October 23, 2020
Every so often, another of those stories pops up. Two doctors in one Australian family are dead from Covid. Four members of one New Jersey family have succumbed, likewise three brothers in Iran. A whole family – mother, father and child – have died from it in the UK. Each time, surely, it raises the question: why? You can blame testing failures, poverty, too few distancing measures or too many, for crowding families together, or any other political or economic factor you choose. But perhaps we spend too little time considering the hundreds of factors that have little to do with our politicians: some families, for example, may be genetically predisposed to get severe Covid.
Over the summer a UCL scientist called Karl Friston attracted a flurry of media interest when he suggested that the reason for different Covid outcomes in different countries may be something he termed “immunological dark matter”. The idea was that some populations simply happen to have more existing immunity to Covid-19, perhaps due to the particular mix of coronaviruses they have caught and fought off in the past. This, rather than Germany’s exemplary competence and early testing capacity, may be why that country has not suffered as much from the pandemic as many of its neighbours, he theorised.
Even more nightmarish for government policy, our genetic makeup also seems to affect our propensity to get severely ill and die. One study by the Covid-19 Host Genetics Initiative found that for some Covid patients with a particular set of genes, being in blood group A seemed to be associated with a higher risk of respiratory failure, whereas being in blood group O had the opposite effect. Another study from the Max Planck Institute in Germany looked at those with especially poor Covid outcomes and found they disproportionately possessed a set of genes inherited from Neanderthals. What’s more, these mutations are especially prevalent in people of South Asian origin, who have been so severely affected by Covid, and almost non-existent in those from East Asia.
The genetic picture is extremely complex, however. Like South Asians, black Britons and African Americans have suffered especially bad outcomes from Covid, yet Neanderthal DNA is largely absent from African populations. A study by scientists at Regeneron, a biotech company, found that there may be another gene also associated with poor Covid outcomes and more prevalent in people of African origin. So it isn’t just down to one killer gene, but a person’s susceptibility could well be profoundly affected by her genome and such genetic factors may be just as important as social problems like poor health and poverty in explaining why certain countries and populations seem to be so much more vulnerable than others.