Sa'id bin al-Musayyib (may Allah have mercy on him) said that Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) said: Whoever marries a woman who is insane, or has leprosy (judham) or vitiligo (baras), and then has intercourse with her, must pay the dowry (mahr), and the husband may recover it as a penalty from the woman's guardian.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14222