  The gauge coupling unification is investigated at the classical level under
the assumptions that the gauge symmetry breaking chain is $E_8\to E_7\times U_1
\to E_6\times U_1 \to SO_{10}\times U_1 \to SU_5 \times U_1 \to SU_3 \times
SU_2 \times U_1$ and only components of the representations 248 of $E_8$ can
acquire vacuum expectation values. We demonstrate that there are several
options for the relations between the gauge couplings of the resulting theory,
but the only symmetry breaking pattern corresponds to $\alpha_3=\alpha_2$ and
$\sin^2\theta_W=3/8$. Moreover, only for this option the particle content of
the resulting theory includes all MSSM superfields. It is also noted that this
symmetry breaking pattern corresponds to the case when all representation which
acquire vacuum expectation values have the minimal absolute values of the
relevant $U_1$ charges.
