n class we investigated the reason cystic fibrosis is maintained in the human population in higher frequency than we expected given the deleterious effects of being homozygous at the CFTR gene. We calculated the actual mutation rate of the CFTR gene to be 6.7 x 10-7. The mutation rate expected under mutation-selection balance was 4 x 10-4. What is the most plausible explanation as to why cystic fibrosis is maintained in the human population at a higher frequency than we expect?   a. Negative selection against the CFTR deleterious alleles is too weak to eliminate the alleles from the human population.   b. Positive selection for the CFTR deleterious alleles is likely occurring in response to some other selective pressure in the human population, possibly resistance to typhoid fever.   c. The CFTR gene has an exceedingly low mutation rate causing humans to have no genetic variation at that gene.   d. The CFTR gene has an exceedingly high mutation rate and that is why the disease is maintained at a higher rate than we expect.

Go to the NCBI’s website at https://ncbi.nlm.nih.gov On the database dropdown menu, select “Gene” and search for “RB1.” The first entry should be on the Homo sapiens version; click the gene name. Use the information to answer the following: What is the chromosomal location of RB1? Scroll down to the “Expression” data. List 2-3 examples of normal tissues that typically express the RB1 gene. Would you say that RB1 expression is very specific or general within tissues? Scroll down to the “NCBI Reference Sequences (RefSeq)” section. Click on the “GenBank” link under NG_009009.1 RefSeqGene. This will take you to the genomic sequence of RB1. How many nucleotides long is the full-length RB1 gene? Return to the RefSeq section in the Gene Database for RB1 (back click once from where you were for part c). Click on the link under “mRNA and Protein(s)” listed as NM_000321.3. This will take you to the mature mRNA sequence data: How many bases long is the full-length RB1 mRNA transcript? Scroll…

"Genome-Wide Association Studies Identify Genome Variations That Contribute to Disease" Explain this ?

I'm confused with question 11. Thanks for all your help!