An Excel VBA macro: Alterternate background of each row according to a key column (column C such as "chr1:123-123;A>T")

PhysPosGrouping.vb

Sub PhysPosGrouping()
    Dim oRange As Range
    Dim lRorB As Long
    Dim lColR As Long
    Dim gcount As Long
    
    Set oRange = ActiveSheet.UsedRange
    lRowB = oRange.Row + oRange.Rows.Count - 1
    lColR = oRange.Column + oRange.Columns.Count - 1
    
    For Each e In Range("C2:C" & lRowB)
        If e <> e.Offset(-1, 0) Then
            gcount = gcount + 1
        End If
        If (gcount Mod 2) = 0 Then
            e.EntireRow.Interior.ColorIndex = 15
        Else
            e.EntireRow.Interior.ColorIndex = 0
        End If
    Next e
End Sub