I don't know, but I heard that Finnish and possibly Hungarian [Magyar] are related to Basque.
I had never heard of a connection between the Uralic languages (Finnish and Magyar), and the Basques. We Finns arrived in Europe at the end of the period before Christ, and our Magyar cousins arrived about 1000 years later (slothful, right). I had thought that there was evidence that the Basques had been around in their vicinity so long that some people think that they might actually be Cro-Magnon man!!
This is a fascinating subject, since the whole question of ethnic relationships and decent had become quite un-PC due to the bad uses it had been put to by those who confounded the linguistic term 'Indo-European', with the ethnic term 'Aryan'. For decades after the Nazis, any mention of ethnic, or blood, relationships were a very strict no-no, so that you could say that linguistic affinity, say between Germans and Hindus, was not evidence of a blood relationship. This genetic evidence is forcing this question to become again discussible in polite society. Expect BIG TROUBLE about this from the same people who think that genetics have no effect on behavior. (They think it isn't important, but that you must not talk about it.)