  We explore the quark-mass dependence of two-nucleon systems. Allowed regions
for the scattering lengths in the 1S0 and 3S1 channels as functions of the
light-quark masses are determined from the current uncertainty in
strong-interaction parameters that appear at next-to-leading order in the
effective field theory. Where experimental constraints are absent, as is the
case for the quark-mass dependent four-nucleon operators, we use naive
dimensional analysis. We find it likely that there is no bound state in the 1S0
channel in the chiral limit. However, given the present uncertainties in
strong-interaction parameters it is unclear whether the deuteron is bound or
unbound in the chiral limit.
