Mocking a person with disability is a crime

Dear PAO,

My nephew was born with microphthalmia, a congenital abnormality in which his left eye did not fully grow, leaving the other eye smaller. His classmates would often make fun of him at school. As a result, he would constantly cry every day after school. All of them are over the age of majority. We just want to know if we can file a case against his bullies. If so, what would be their penalty?