jmc

Call the coordinates of point $B$ $(x,y)$. The coordinates of a midpoint are the average of the coordinates of the two endpoints, so we know that $\frac{-2+x}{2}=1$ and $\frac{1+y}{2}=-6$. Solving for $x$ and $y$ gives $x=4$ and $y=-13$. We take the sum of $x$ and $y$ for an answer of $\boxed{-9}$.