Regular Expression (first character matching a-z)

Try something like this:

^[a-zA-Z][a-zA-Z0-9.,$;]+$

Explanation:

^                Start of line/string.
[a-zA-Z]         Character is in a-z or A-Z.
[a-zA-Z0-9.,$;]  Alphanumeric or `.` or `,` or `$` or `;`.
+                One or more of the previous token (change to * for zero or more).
$                End of line/string.