Prader-Willi syndrome is caused by a missing gene on chromosome 15. Normally, parents each pass down a copy of this chromosome. The defect can occur in a couple of ways: The father's genes are missing on chromosome 15.
: easy for the mind to understand or recognize. 1  It was obvious that things weren't working out. 2  Her reasons for leaving were obvious. = It's obvious why she left. 3  The answer seems obvious enough to me.  The problem was immediately obvious to everyone in the 1  room. He was the obvious candidate/choice for president.
Evident definition, plain or clear to the sight or understanding: His frown made it evident to all that he was displeased. It was evident that the project was a total failure. See more.