Erechthonius certainly looks like he ought to be associated with Asclepius, since he's portrayed either as a serpent or a sort of hybrid half-man/half-serpent. Erechthonius is a purely Athenian deity, however, and when he's associated with a god at all it is generally with his mother, Athene.

If you're wondering how a virgin goddess could be a mother, think back to the story recounted on the Hephaestus "Deity of the Week" page about how an overexcited Hephaestus dropped semen onto Athene's thigh and it came to fruition even though she hastily wiped it off with a piece of cotton and hid the cotton in a box. The story is told by the crow in the selection from Ovid's Metamorphoses that I assigned for September 20, in her unheeded warning to Apollo's talkative raven.