Well, where do I start. He has a high palate which restricts his nose breathing, so he breathes through his mouth. This is starting to have an effect on his bottom jaw, so the palate needs expanding and he needs trained to breathe through his nose.
His ears are congested and he has slight hearing loss again because the palate encroaches on the space needed for the tubes to drain.
He had really bad reflux and aerophagia which is now almost resolved since he had his tt done in January. He suffered from loads of stomach upsets when he was younger
In the past, he has suffered snoring and sleep apnoea. This stopped last year after his mouth grew a bit, but it's not to say that it won't come back.
His adult teeth are already lining up to come in crooked (he had a dental xray last week) and he already needs braces to sort it.
There seems to be a link with tongue tie and allergies and intolerances, many tongue tied kids are also allergic or intolerant. DS1 outgrew an egg allergy aged 4 and had a nasty milk intolerance until recently.
Um, I'm sure there's more, but these are the main things off the top of my head.