Simplify the following text for a Grade 12 native English-speaking person.
Original: Other limb onset patients first see the effects of the disease on a hand or arm as they have a difficult time with simple tasks requiring hand dexterity , or ability to move small things , such as buttoning a shirt , writing , or turning a key in a lock .
Simplified: Arm-onset patients may experience difficulty with tasks requiring manual dexterity such as buttoning a shirt , writing , or turning a key in a lock .