What would happen/Is it possible

[MTL]

So these are two questions, not one[All for curiosity, of course. ]

1st: Is it possible that someone can have a growth/birth defect(idk what to call it) that causes rapid brain growth, kind of like how some people have rapid overall growth(as in they get super tall), and other things to that nature. I know it's possible for the rest of the body, but could it possibly apply to the brain?

2nd: Assuming this was possible, what do you think would happen? What would be the consequences? If from infancy to adulthood your brain grew triple the normal speed, you can imagine the amount of brain capacity you would have would make you exponentially smarter, or maybe it wouldn't, what do you think?

I have an unpleasant idea as to what might occur.

(Warning, not for the sensitive, especially for animal lovers, dog lovers):

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Due to overbreeding, the population of Cavalier King Charles Spaniels in the UK
began to demonstrate an appalling genetic fault, a few years ago:

Their brains grew faster....and ultimately larger...than their skulls.

The result was nothing short of tragic and horrific:

dogs having seizures and/or writhing on the ground, screaming in agony,
that had to ultimately be destroyed.

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