Variant Phasing

[zhuchcn]

We should consider the support for variant phasing to reduce the graph complexity.

For germline variants, we could take the ShapeIT phased, and VEP annotated VCF, and directly keep the phasing information. For each variant, we can keep this information in the phase_set info field.

[zhuchcn]

Alternative splicing events may also be "phaseable" (not sure if this is the right term) using long-read RNA-seq data.