Bernie Sanders' family connections to the Holocaust

I see in several news site (and on Wikipedia) that Sanders’ father’s relatives were killed in the Holocaust. I’m curious about the specific connection.

Surely his father’s relatives are also his relatives. But who? Aunts, uncles, grandparents, cousins, second cousins?

The question is a purely genealogical one rather than one of politics or identity.

In Wikipedia it mentions specifically Romek, his paternal uncle as being murdered by the Nazis, it also mentions that many of his mother’s relatives were killed (presumably Bernie’s maternal great uncle/aunts and second cousins as it says his mother was born in the USA in 1904).