Food for thought, a paragraph taken from this link(
http://www.helendowland.fasthit.net/What%20is%20a%20gifted%20child.htm):
"However - experience has taught me that IQ tests are not infallible, and that there are children who are clearly gifted, who don't score highly on their IQ test. (The term "clearly gifted" is hard to explain succinctly - basically it means a child who is clearly able to do many things that are usually only done by much older children. Also see the page "How do I know if my child is gifted?") In recent years the problem with IQ tests has mostly been due to the use of out-dated or inappropriate IQ tests, because a modern test that was appropriate for gifted children wasn't available (see the explanation on the page "Testing Gifted Children"). Since 2005 the new Stanford Binet 5 test has been available, and this is the only test that should now be used for gifted children; parents should ask insistantly for this test, in order to require psychologists to move on from the much-used WISC-III, which was never appropriate to test gifted children (again, see "Testing Gifted Children").
Even so, there are various factors that can cause a lower IQ test than a child's "giftedness" would indicate. A common reason for this is that a gifted child may have neural "glitches", which show up in the school context as Specific Learning Difficulties; these can cause the child to score lower on some subsets of the IQ test, causing the overall "IQ" to be lower. The child may therefore have giftedness that is very apparent in his/her conceptual ability and general understanding, but in some of the neural tasks that we usually take for granted s/he may have difficulty. I have included an introduction to some aspects of Learning Disabilities in gifted children on the page "Gifted Learning Disabled"; do refer to this page as it has some very helpful practical information, but also do search further because this is a vast field. Gifted children with learning disabilities are now being called "Twice Exceptional". In the case of a child who scores at a gifted level on many of the subsets of an IQ test, but scores lower on some subsets that are clearly related to dyslexia, auditory processing problems, or some other neural glitch, I always still regard that child as "gifted" - he or she is, as the new terminology says, twice exceptional - exceptional in being gifted, and exceptional in having some form of processing difficulty; such a child will need help for the issues of both these exceptionalities.
However, sometimes the cause of low scores on an IQ test, by a child who is clearly gifted, even highly gifted, simply remains unknown. Do they think too much "outside the box", or do they have a particular nervousness in the testing situation? - unknown. In my experience cases like this are rare, but they do occur. Ultimately, if he/she seems like a gifted child, thinks like one and acts like one, s/he very probably is one."
