Angela
Elite member
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So asks Iain Mathiesen.
See: Ben Kraus-Kyora
"Ancient DNA study reveals HLA susceptibility locus for leprosy in medieval Europeans"
https://www.nature.com/articles/s41467-018-03857-x
I thought it was a hot weather disease, no?
"Leprosy, a chronic infectious disease caused by Mycobacterium leprae (M. leprae), was very common in Europe till the 16th century. Here, we perform an ancient DNA study on medieval skeletons from Denmark that show lesions specific for lepromatous leprosy (LL). First, we test the remains for M. leprae DNA to confirm the infection status of the individuals and to assess the bacterial diversity. We assemble 10 complete M. lepraegenomes that all differ from each other. Second, we evaluate whether the human leukocyte antigen allele DRB1*15:01, a strong LL susceptibility factor in modern populations, also predisposed medieval Europeans to the disease. The comparison of genotype data from 69 M. leprae DNA-positive LL cases with those from contemporary and medieval controls reveals a statistically significant association in both instances. In addition, we observe that DRB1*15:01 co-occurs with DQB1*06:02 on a haplotype that is a strong risk factor for inflammatory diseases today."
"A recent ancient DNA (aDNA) analysis has revealed a high level of M. leprae genome conservation over the past 1000 years, indicating that the leprosy epidemic during the European Middle Ages was unlikely to be due to particularly virulent strains2. Instead, other factors such as malnutrition, co-infections, and host genetics may have increased disease susceptibility in the medieval period. At present, leprosy is virtually absent in Europe, but still remains a big health problem in South-East Asia (e.g., India), North and Central Africa (Central African Republic, Democratic Republic of the Congo), Oceania (Indonesia, Papua New Guinea) and the Americas (Brazil, Mexico)3. All 10 modern human M. leprae genomes sequenced up to now fall in five distinct phylogenetic branches that show a specific geographic distribution pattern2."
"Leprosy was endemic during the Middle Ages in Europe, where it reached its greatest prevalence between AD 1200 and 14001. "
"Among the St. Jørgen samples, branch 3-strains were most abundant (n = 9) and very similar to extant strains recently identified in European red squirrels21 (Fig. 3). Interestingly, modern branch 3-bacteria have the ability to infect at least three different hosts including humans and squirrels21"
It's the damn rodents again.
"The comparison of the rs3135388-T frequencies from the 69 LL cases with the DRB1*15:01 data from modern controls revealed a statistically significant association. To strengthen this finding, we further analyzed whether the allele frequency in the cases was different from that of medieval controls. The controls (i) were selected from sites that were geographically close and dated earlier or contemporaneous to St. Jørgen, (ii) showed no osteological evidence of the severe LL form of the disease and (iii) were M. leprae DNA-negativ."
"Notably, the medieval control frequency was slightly but significantly higher than today (p = 0.024, OR = 1.41, Table 1), possibly indicating weak selection against this allele during or since medieval times. This observation raises the question of how leprosy might have led to reduced reproductive fitness given that affected people, at least in modern populations, rarely die from the disease. "
Mathiesen's question is based on this:
"Note that the rs3135388 T allele was introduced to Europe by Bronze Age Steppe migrations.
[/IMG]
I don't know what to think about this. Did steppe samples from the Bronze Age show signs of leprosy? Was there no sign of it in Europe before the Middle Ages.
If it's true it must have been like the Apocalypse and the four horsemenestilence, War, Famine, and Death.
See: Ben Kraus-Kyora
"Ancient DNA study reveals HLA susceptibility locus for leprosy in medieval Europeans"
https://www.nature.com/articles/s41467-018-03857-x
I thought it was a hot weather disease, no?
"Leprosy, a chronic infectious disease caused by Mycobacterium leprae (M. leprae), was very common in Europe till the 16th century. Here, we perform an ancient DNA study on medieval skeletons from Denmark that show lesions specific for lepromatous leprosy (LL). First, we test the remains for M. leprae DNA to confirm the infection status of the individuals and to assess the bacterial diversity. We assemble 10 complete M. lepraegenomes that all differ from each other. Second, we evaluate whether the human leukocyte antigen allele DRB1*15:01, a strong LL susceptibility factor in modern populations, also predisposed medieval Europeans to the disease. The comparison of genotype data from 69 M. leprae DNA-positive LL cases with those from contemporary and medieval controls reveals a statistically significant association in both instances. In addition, we observe that DRB1*15:01 co-occurs with DQB1*06:02 on a haplotype that is a strong risk factor for inflammatory diseases today."
"A recent ancient DNA (aDNA) analysis has revealed a high level of M. leprae genome conservation over the past 1000 years, indicating that the leprosy epidemic during the European Middle Ages was unlikely to be due to particularly virulent strains2. Instead, other factors such as malnutrition, co-infections, and host genetics may have increased disease susceptibility in the medieval period. At present, leprosy is virtually absent in Europe, but still remains a big health problem in South-East Asia (e.g., India), North and Central Africa (Central African Republic, Democratic Republic of the Congo), Oceania (Indonesia, Papua New Guinea) and the Americas (Brazil, Mexico)3. All 10 modern human M. leprae genomes sequenced up to now fall in five distinct phylogenetic branches that show a specific geographic distribution pattern2."
"Leprosy was endemic during the Middle Ages in Europe, where it reached its greatest prevalence between AD 1200 and 14001. "
"Among the St. Jørgen samples, branch 3-strains were most abundant (n = 9) and very similar to extant strains recently identified in European red squirrels21 (Fig. 3). Interestingly, modern branch 3-bacteria have the ability to infect at least three different hosts including humans and squirrels21"
It's the damn rodents again.
"The comparison of the rs3135388-T frequencies from the 69 LL cases with the DRB1*15:01 data from modern controls revealed a statistically significant association. To strengthen this finding, we further analyzed whether the allele frequency in the cases was different from that of medieval controls. The controls (i) were selected from sites that were geographically close and dated earlier or contemporaneous to St. Jørgen, (ii) showed no osteological evidence of the severe LL form of the disease and (iii) were M. leprae DNA-negativ."
"Notably, the medieval control frequency was slightly but significantly higher than today (p = 0.024, OR = 1.41, Table 1), possibly indicating weak selection against this allele during or since medieval times. This observation raises the question of how leprosy might have led to reduced reproductive fitness given that affected people, at least in modern populations, rarely die from the disease. "
Mathiesen's question is based on this:
"Note that the rs3135388 T allele was introduced to Europe by Bronze Age Steppe migrations.
I don't know what to think about this. Did steppe samples from the Bronze Age show signs of leprosy? Was there no sign of it in Europe before the Middle Ages.
If it's true it must have been like the Apocalypse and the four horsemenestilence, War, Famine, and Death.