How would the absence of juxtamedullary nephrons affect the volume of urine and its osmotic concentration?

Increase volume; decrease osmotic concentration

Explanation:

Nephron is the functional unit of a kidney.

The juxtamedullary nephrons is responsible for the development of the osmotic gradients. The osmotic gradient helps in ensuring the urine is well concentrated and helps in adequate water reabsorption.

The absence of juxtamedullary nephrons affect the volume of urine and its osmotic concentration by Increasing the volume and decreasing the osmotic concentration.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."