The Torah says Pharaoh gave Joseph a wife named Asenath, daughter of Potiphera, priest of On. Targum Pseudo-Jonathan on Genesis 41:45 stops the reader short with a different claim: Asenath was "whom Dinah had borne to Shekem, and the wife of Potiphera prince of Tanis had brought up."
Keeping the marriage inside the family
The Aramaic paraphrase, which reached its final form in the Land of Israel around the seventh or eighth century CE, cannot let Joseph marry outside the household of Jacob. The same tradition appears in Pirkei deRabbi Eliezer, chapter 38, a Jewish narrative midrash composed around the eighth or ninth century CE: after Dinah's violation (Genesis 34), she bore a daughter, and the archangel Gabriel carried the infant to Egypt, where she was adopted into Potiphera's household. When Joseph rose to power and married "Asenath," he was in fact marrying his own niece — a descendant of Jacob all along.
Pharaoh also gives Joseph a name
The verse also preserves Pharaoh's Egyptian title for Joseph: the Targum translates Tzafenat Paneach as "The man who revealeth mysteries." A name earned in the dream chamber becomes the official court title he will carry for the rest of his life.
The takeaway
The Targum refuses to let Joseph's family tree fray at the edge. Even in the Egyptian court, even under an Egyptian name, the line of Abraham is kept unbroken.