Flakey toe nail cause (pic)

[Miljea]

What do you think is causing this flaking on the tip of DS's big toe nail(s)?

He's 21 and has had it for probably 5 years!

It's like they're delaminating, but they're not bumpy or 'disfigured'.

I have a couple of fungal nails 😬 but they don't look like this.

Any ideas?

Psoriasis?

Don't know but will follow the thread - our 10yo son has this on both big toes, one more affected than the other. No sign of fungal infection (I know from personal experience what that looks like!) I was wondering about a vitamin deficiency ...

I've read that anaemia might be a factor. Tho DS takes a multivitamin every day with iron (uni student).

Any other ideas?