All I really know about that condition is how it affects my friend and that it's genetic. But I was kinda curious so I went to the Wikipedia article (linked above).
Which includes the quote: "It is characterised by (....) an unusually cheerful demeanor (...) a love of music (...)"
I know, it's wikipedia and you gotta take it with a huge pinch of salt. But I don't know whether to find that insulting or amusing.
Clearly if you are a particularly cheerful person and love music you might just have Williams Syndrom (or at least according to Wikipedia you might)
It's 1.32 AM. why am I still up?!