Practicum Project: NIH's Medical Mystery

NIH's Medical Mystery: A Patient With Symptoms of Fucosidosis Lacks The Disease-Causing Fucosidase Deficiency

For my practicum project, I volunteered my assistance to the researchers at the National Institues of Health (NIH), specifically, NHGRI (National Human Genome Research Institute). I worked in the laboratory on a project that these researchers have been working on since about November of last fall. A patient had been sent to the NIH for treatment because no other institute had been able to determine the cause of Patient X's disease and symptoms. Patient X showed symptoms of a Lysosomal Storage Disorder (LSD) in which the patient's lysosomes were storing the body's waste materials rather than degrading them like usual. This extra storage caused the cells to swell and occassionally burst causing malfunction of cell processes which led to disease. Specifically, Patient X showed signs of the LSD known as Fucosidosis which is caused by an enzyme deficiency of the fucosidase enzyme, however, when Patient X's fucosidase activity was assayed, it was found to be functioning at 100% of the level of activity found in normal, unaffected cells. Since the day of the discovery that Patient X's fucosidase activity was normal, several other enzymes known to cause LSD's were assayed. During my time at NIH, I aided in performing the various enzyme assays, and as it turns out, one of the enzymes I had been assigned to work with displayed activity levels that were functioning at about 50% of the normal level of activity found in unaffected cells. I had discovered which enzyme deficiency was at play here, however, it is quite possible that more than one enzyme was contributing to the disease. The enzyme abbreviated as GalNAc was only half functional within Patient X's cells, and so far, that is the only enzyme that has been found to be functioning at less than 100%. I was very excited to be able to experience the jubilant excitement in the lab the day we had figured out the main cause of the disease. It was a very fulfilling climax of my practicum, and I am so thankful to Dr. Krasnewich, the researcher leading the project, for allowing me to spend some time with her and her team. I was able to get a feel for what real lab-work was like, and it helped me to solidify my decision to become a research geneticist. Having had an internship in high-school at a hospital with hands on patient interaction, I have now been able to experience the "Doctor's World" as well as the "Researcher's World," and I am certain that I enjoy the lab research much better. Thank you to all who helped me in obtaining one of the most fulfilling interships I have ever been able to experience! For a brief overview of the research, see below:

Abstract:

During my time at the National Institutes of Health (NIH), I was part of a team that was attempting to uncover the disease-causing agent in one of their patients who was suffering from a Lysosomal Storage Disorder (LSD). Lysosomes are organelles within the cells of the body that are supposed to break-down the cell’s waste materials, package the material, and send it to the cell membrane to be exported, but when the lysosome stores these wastes without breaking them down or getting rid of them, the waste material accumulates and causes the cells to bulge. This bulging results in an LSD. There are many types of LSD’s and the problem that the doctors and researchers at NIH were experiencing was that Patient X showed many of the signs and symptoms of an LSD known as Fucosidosis which is due to an alpha-L-fucosidase enzyme deficiency, but test results showed that Patient X’s alpha-L-fucosidase enzyme activity was normal. This result was shocking in that the activity tests of Patient X’s cells should have displayed a decreased amount of activity compared to the control cells. The first thought was that the control cells were inadequate for use in the experimental tests, so to correct the problem, a new set of control cells were used. The same tests were repeated with the new control cells, and surprisingly, the same results were obtained. Patient X’s cells showed normal levels of activity for the alpha-L-fucosidase enzyme. Subsequently, we began performing experiments that examined other enzymes known to cause LSD’s. To accelerate the process, each member of the team performed an enzymatic activity assay on a different enzyme. I chose to work with the N-acetyl galactosamine enzyme, more commonly known as GalNAc. The first trial showed that Patient X’s cells were only functioning at about 50% of the normal level of activity. Thinking that the assay had been performed incorrectly, further trials were completed, but each trial revealed the same results. Therefore, the LSD in Patient X was due to malfunctioning GalNAc, even though the signs pointed to Fucosidosis.

Making Glycine for the Enzyme Assays at NIH

NIH Labwork!!!

Before starting the enzyme assays, it was important to make sure the Glycine, the agent that stops the enzymatic reactions, was up-to-par and working properly.