Rashi on Genesis
'וינגע ה' וגו AND THE LORD PLAGUED PHARAOH etc. — He was smitten with the disease of Raathon for which marital relations are harmful.
Ramban on Genesis
BECAUSE OF SARAI ABRAM’s WIFE. This means that because of the wrong done to Sarah, as well as to Abraham, and the merit of both of them, these great plagues came upon Pharaoh and his house.
Sforno on Genesis
וינגע ה' את פרעה נגעים גדולים, only Pharaoh was struck with “great” afflictions,