Does cilantro taste like soap? It sure does if you have the gene that detects PTC. Although that is not an example of a taste disorder it is an example of an gene that has been identify to affect how we perceive taste. Although true taste loss (aguesia) is exceedingly rare, hypoguesia and disguesia are a little more common.  
1. Briefly describe the condition and its etiology (genetic, traumatic, environmental).
2. Explain the physical changes involved that lead to the hyper, hypo or nulled sensation. 
3. Site your sources