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.
(dÄfâ²É-nÄ­t) adj. 1. a. Clearly defined; explicitly precise: a definite statement of the terms of the will. See Synonyms at explicit. b. Forthright and unambiguous: The doctor was very definite about what foods you should avoid.