My previous post dealt with the anomalous prevalence of Alzheimer's Disease among American Natives, today's deals with another "unique" Amerindian genetic trait, that extends to what in USA are known as Latinos (people with mixed ancestry that includes Native Americans): one that protects against breast cancer.
The table above clearly shows how American Natives and Latinos have the lowest incidence of Breast Cancer among American women.
The cause according to a paper  by Laura Fejerman et al.,(2014) is a mutation in chromosome 6: "Here we carry out a genome-wide association study of breast cancer in Latinas and identify a genome-wide significant risk variant, located 5′ of the Estrogen Receptor 1 gene (ESR1; 6q25 region). The minor allele for this variant is strongly protective (rs140068132: odds ratio (OR) 0.60, 95% confidence interval (CI) 0.53–0.67, P=9 × 10−18), originates from Indigenous Americans and is uncorrelated with previously reported risk variants at 6q25."
This mutation is the reason that "Latina women, those with a high proportion of Indigenous American ancestry are at a lower risk of developing breast cancer..." .
This mutation must have appeared in America otherwise the purported ancestors of Amerindians (as per the Out of Africa theory) would also carry this variant. By the way, the prevalence of Cancer among Amerindians is almost 1/3 of that found among White American women and half of that found among African American women. The Asian Americans' ratio is also almost twice that of American Natives. (these are supposedly the closest genetic relatives to Amerindians).
Is this also due to a bottleneck? or is did it appear during the "Beringian standstill"?
What does the genome of Neanderthal or Denisova tell us about this mutation? I have tried to find information but have not found anything. It may be a mutation inherited from them. Found only in America.
But what about Papuans, who have a high proportion of Denisovan genes? I found two papers (here) and (here) which inform extremely low levels of cance: roughly 8 to 20 times lower than the ratio among Ameridians"!: from 1958 to 1988, the incidence of breast cancer was betwenn 6.9 and 2.4 per 100,000 women.
Do Papuan women have a genetic mutation that protects them too? or is it just lifestyle? Or are these numbers not adjusted by age?
I found another interesting source (global Cancer atlas) which lists cancer prevalence among all human populations. I selected Breast Cancer Incidence and got this map:
Clearly this differs from the other information: dark blue= EU, Australia, America and NZ, Argentina... countries with a high prevalence of White Europeans that eat beef. And low prevalence in "poor" countries where fatty foods are not so common... Asia, Africa, Bolivia. The quality of the data is also variable, ranging from "A" in the US to "C" in China or "G" in Bolivia (19.2 per 100,000 cases) so it makes me wonder how reliable this information is.
Anway, the intersting point is the mutation in Chromosome 6 found among Native American women.
 Zhang and Olopade in Hereditary Breast Cancer. Edited by Caludine Isaacs, T.Rebbeck. pp.234
 Laura Fejerman, et al.,(2014). Genome-wide association study of breast cancer in Latinas identifies novel protective variants on 6q25, Nature Communications 5, Article number: 5260 doi:10.1038/ncomms6260
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