3 人类有 3%的尼安德特人基因，这对我们是福是祸？
DNA from Neanderthals affects vulnerability to covid-19
来自尼安德特人的 DNA 会影响对新冠肺炎的易感性
In the past decade it 1_____(become) clear that Neanderthals mated(交配) with the ancestors of modern humans, and that at least some of those unions produced viable(可发育的) offspring（后代）. The upshot（结论） is 2____ almost half of the Neanderthal genome(基因) still survives, scattered in small quantities among almost all modern people's DNA.
Many such genes seem to be 3_____(relate) to the immune system, and to affect the risk of developing diseases including lupus(狼疮), Crohn's（克罗恩氏症） and diabetes（糖尿病）. A pair of recent papers suggest covid-19（新冠） belongs on that list as well.
The first paper, 4_____(publish) in Nature in September, described one Neanderthal DNA string, known as a "haplotype"(单倍型), is associated with a higher risk of serious illness.
That genetic bad luck is not evenly distributed. The gene-sequence is most common among people of South Asian descent, 5_____ 63% of the population of Bangladesh(孟加拉国) carrying at least one copy.
The second study concerns another Neanderthal haplotype, found on chromosome （染色体）12. Its effect is 6_____(protect), though it is also less potent: having a single copy is associated with a 22% 7_____(low) chance of critical illness. This helpful sequence is more well-travelled than the harmful one. It is present in every part of the world except sub-Saharan Africa(撒哈拉以南非洲).
The 8_____(researcher) hope that their work might help shed light on 9_____some countries, and some populations within countries, appear to have been hit harder by covid-19 than others. But disentangling (分离)the effects of DNA will be tricky. Comparisons between countries are also complicated by definitional differences and the difficulty of performing accurate counts, 10_____( especial) in poor countries.
Still, a reminder that genetics matter alongside those other factors is still useful.
Keys:
1 has become 2 that 3 related 4 published 5 with
6 protective 7 lower 8 researchers 9 why 10 especially
