Why did all the leaves on my golden euonymous shrub die and fall off?

I live in northern Ohio....My children bought me two of these small shrubs for Mother's day.....But through the winter, I noticed the leaves turned brown and with a touch they just fall off.....I do see some new growth toward the bottom of the branches...Should I just prune that top or what....I would appreciate any help to keep my golden euonymous shrubs alive thank you.

Why did all the leaves on my golden euonymous shrub die and fall off?
It could be a Powdery Mildew: Powdery mildew is the most common and possibly the most difficult disease to control on euonymus. It is caused by the fungus Oidium euonymi-japonici. Symptoms consist of a flat, white to gray growth primarily on the upper surfaces of the leaves, which can be rubbed off easily. Leaves may yellow slightly and drop, but heavy leaf drop is not a characteristic symptom. On young shoots leaves can become curled and scarred if infection is severe.
Reply:pruning is a good thing to do. many plants loose their leaves in the winter.