Iterate on a list coming from a variable

I’d like to iterate over a list of values, which is stored inside a variable.

The problem is that the list of items (myList in the MWE) to iterate over is the value of a previously-declared variable (mydata).

This nested declaration breaks the iteration, as shown in the MWE. Indeed, iterating over myData does not give any problems while iterating over myList does.

documentclass{article}
usepackage{pgffor}
setlengthparindent{0pt}
defmyData{1,2}
defmyList{myData}

begin{document}
section*{Variables}

Mydata : myData

Mylist : myList

section*{Iteration over myList} 
Somewhere this is broken due to the variable declaration...

foreach x in myList
{
    Item x 
}

section*{Iteration over myData}

foreach x in myData
{
    Item x 
}
end{document}

How can I make the variable re-definition not break the iteration ?
I cannot do otherwise since this MWE is a excerpt of a much broader project.

documentclass{article}
usepackage{pgffor}
setlengthparindent{0pt}
defmyData{1,2}
edefmyList{myData}

begin{document}
section*{Variables}

Mydata : myData

Mylist : myList

section*{Iteration over myList}
Somewhere this is broken due to the variable declaration...

foreach x in myList
{
    Item x 
}

section*{Iteration over myData}

foreach x in myData
{
    Item x 
}
end{document}