Lilac tree disease

Vladka Bontenbal

Would anyone know what disease this might be and how to treat it? The leaves have this problem right from the start in the spring, some of them are hanging like they do not have water and at the end of the summer the leaves are all scrolled or/and brown. Thank you😉

AnniD

I thought the leaf damage looked as though it was possibly caused by some kind of leaf miner.
I found this information on the RHS website which might be of some use,  failing that hopefully someone else can advise 
https://www.rhs.org.uk/advice/profile?pid=892