Responsible Mentoring, Disabilities

Description of the Problem

A young graduate student in the middle of his thesis research is diagnosed with a debilitating chronic disease. The recurrence of the condition results in his being absent from the laboratory for extended periods of time. Ultimately, he falls seriously behind in his research. This poses a dilemma for his mentor, who, while wanting to be supportive of the suffering student, has an obligation to his research sponsor to be productive scientifically.

To complicate matters, the student is from another country, and if he loses his student status, he will have to leave the US.

Question

What course of action should the mentor take that might not undermine the student and yet at the same time carry out his responsibilities?
Responsible Mentoring, Disabilities Discussion