Question

6. McCoy et al. (2017) chose to study modern human subjects who were heterozygous for Neanderthal-specific SNPs that were transcribed into mature mRNAs. Why (how) were individuals with these genotypes helpful for gene expression assays? The authors found a systematic bias in their results, in which the Neanderthal alleles tended to be down-regulated in the brain and the testis, more often than in other tissues. What could account for this?

from here : McCoy, R. C. et al. (2017) Impacts of Neanderthal-introgressed sequences on the landscape of human gene expression. Cell 168, 916-927.

Answer 1

Neanderthal specific SNPs has undergone introgression in ansient time. Due to the hibridisation between neaderthal human and modern human some of these parts of DNA remains still in the modern human. so invividuvals with these genotypes were help full to study the gene expression of the tagged genes and transcriptional variations and selective rgulation of the genes from genetic pool. the tissue specific down regulation in brain tissue mainly occurs in cerebellum and basal ganglia. this parts of brain where genes might show less overall allile specific gene expression.

in testes also the downreggulation of neanderthal alliles are significant. in these genes purifying selection disproportionally removed neanderthal haplotypes. these findings have shown similarity to the finding that hybrid males some times infertail. so this down regulation might have atributed to the evolutionary benefit