It is interesting to note that as far as neo-Darwinism has actually influenced medical diagnostics, which hasn't been that much, it has led to medical malpractice:
Evolution's "vestigial organ" argument debunked
Excerpt: "The appendix, like the once 'vestigial' tonsils and adenoids, is a lymphoid organ (part of the body's immune system) which makes antibodies against infections in the digestive system. Believing it to be a useless evolutionary 'left over,' many surgeons once removed even the healthy appendix whenever they were in the abdominal cavity. Today, removal of a healthy appendix under most circumstances would be considered medical malpractice" (David Menton, Ph.D., "The Human Tail, and Other Tales of Evolution," St. Louis MetroVoice , January 1994, Vol. 4, No. 1).
"Doctors once thought tonsils were simply useless evolutionary leftovers and took them out thinking that it could do no harm. Today there is considerable evidence that there are more troubles in the upper respiratory tract after tonsil removal than before, and doctors generally agree that simple enlargement of tonsils is hardly an indication for surgery" (J.D. Ratcliff, Your Body and How it Works, 1975, p. 137).
The tailbone, properly known as the coccyx, is another supposed example of a vestigial structure that has been found to have a valuable function—especially regarding the ability to sit comfortably. Many people who have had this bone removed have great difficulty sitting.
Surgical removal of the tonsils and appendix associated with risk of early heart attack - June 2011
Excerpt: The surgical removal of the appendix and tonsils before the age of 20 was associated with an increased risk of premature heart attack in a large population study performed in Sweden. Tonsillectomy increased the risk by 44% (hazard ratio 1.44) and appendectomy by 33% (HR 1.33). The risk increases were just statistically significant, and were even higher when the tonsils and appendix were both removed.
International HoloGenomics Society - "Junk DNA Diseases"
Excerpt: A primary goal of IHGS is to elevate awareness of the fact that "some, if not all" hereditary diseases do not stop at the boundaries of "genes"
Excerpt: "elaborated in more detail in my “Obituary of Junk DNA “
,,,uncounted millions of people died miserable deaths while scientists were looking for the “gene” causing their illnesses – and were not even supposed to look anywhere but under the lamp illuminating only 1.3% of the genome (the genes)."
"Certainly, my own research with antibiotics during World War II received no guidance from insights provided by Darwinian evolution. Nor did Alexander Fleming's discovery of bacterial inhibition by penicillin. I recently asked more than 70 eminent researchers if they would have done their work differently if they had thought Darwin's theory was wrong. The responses were all the same: No.
Philip S. Skell - (the late) Professor at Pennsylvania State University.
Darwinian Medicine and Proximate and Evolutionary Explanations - Michael Egnor June 2011