  The minimal supersymmetric standard model with complete, partial or no Yukawa
unification and radiative electroweak breaking with boundary conditions from
the Horava-Witten theory is considered. The parameters are restricted by
constraining the lightest sparticle relic abundance by cold dark matter
considerations and requiring the b-quark mass after supersymmetric corrections
and the branching ratio of b --> s gamma to be compatible with data. Complete
Yukawa unification can be excluded. Also, t-b Yukawa unification is strongly
disfavored since it requires almost degenerate lightest and next-to-lightest
sparticle masses. However, the b-tau or no Yukawa unification cases avoid this
degeneracy. The latter with mu<0 is the most natural case. The lightest
sparticle mass, in this case, can be as low as about 77 GeV.
