  We consider bound states in the continuum (BICs) in a 1D multilayered system
of an anisotropic defect layer embedded into an anisotropic photonic crystal.
We analytically demonstrate that an anisotropic defect layer embedded into
anisotropic photonic crystal supports accidental BICs. These BICs can be
transformed to a high-Q resonances by variation of one of the system's
parameters. At the same time the BICs are remarkably robust in a sense that a
true BIC can be recovered by further tuning any of the other system's
parameters leading to tunability of the resonance position.
