Is it permissible to seek divorce from a husband who concealed his hereditary vitiligo, which is present in him and his siblings, and which causes repulsion, anger, and an unwillingness to have children?

If it becomes clear that your husband's nephews and nieces are afflicted with leprosy (al-baras), and it is hereditary, and you fear that your children might also be born with it, then it is permissible for you to seek divorce. This is considered a valid excuse. The jurists (fuqaha') have mentioned in their reasoning for the permissibility of annulment (faskh) that if a husband or wife has leprosy, and there is fear of it being transmitted to the offspring, then it is allowed. Ibn Qudamah, may Allah have mercy on him, said: "Indeed, leprosy (al-judham) and al-baras arouse aversion in the soul, preventing intimacy, and there is fear of them affecting the person and the offspring, thus hindering enjoyment." Psychological harm falls under the category of hardship that permits seeking divorce.