Discuss a disease caused by unequal crossing-over, its symptoms and discuss how the unequal crossing over lead to the symptoms.

Crossing over is a key process occurring in meiosis that leads to genetic diversity. However, crossing over does not always go smoothly and an unequal exchange of chromosome pieces can occur. This is known as unequal crossing-over or nonreciprocal recombination.
All have to be answered:
1. Pick a disease caused by unequal crossing-over.
2. What are the symptoms of this disease?
3. How does the unequal crossing-over lead to the symptoms?
4. Is this disease hereditary (can it be passed on to offspring)?
5. Do you think unequal crossing-over could ever be beneficial? Why or why not?
I need citation with the link so I can get to the source.