Yes it is, but not in the way that we think it. The numbers and symbols we created are only representative of something real. But the laws of physics are concrete mathematical absoloutes. Electrons rely on probablity fields it's crazy stuff out there. Scientists are beginning to discover that the existence of ANY particle could very well be not real at all outside of the narrow realm of mathematical information contained within
Since math is the language of the universe, it follows that all existence is born of mathematics. In fact, we can explain most of the things that happen in biology by using mathematical functions. I think this question is trying to get at the existence of God, but this is not the way to go about it.
To me, this question is asking whether math is the most core and central of all disciplines, and in some ways, it really is. For example, psychology is just biology, but biology is really chemistry. Then you consider that chemistry is actually just the physics of particles, except that physics just comes down to math in the end. For this reason, the realities of math basically underlie existence.
Is mathematics the underlying expression of the universe or is it a language we have developed to describe it? I don't think this question permits of an answer any more than does the existence of God. But I do think that humans only view existence through their own perceptual framework and mathematics is our way of describing what we see. It's possible that "our" existence is describable through the language of math, but there is more to existence than what we can see.
Although this is a loaded question, with endless conclusions and possibilities...I don't think all existence is born of mathematics. I believe there had to be a greater power, god perhaps, that made existence. There is no 100% compelling evidence on either end. but when it comes down to basing it all on math, I can't see how it would come down to math.