No. “This gene has multiple heterozygous loci” is not enough by itself to justify phased reruns.
What matters is not the raw count of hets, but whether the actual cis arrangement inside the model’s input sequence can change the prediction. AlphaGenome takes 1 Mb of DNA sequence as input and scores the exact REF and ALT sequences you provide. It does not reconstruct your diploid chromosomes for you behind the scenes. So phase matters when different hets could combine differently on hap1 versus hap2 and that difference is relevant to the output you care about.
Also, many genomic variants likely have no appreciable impact, according to the AlphaGenome docs. So the fact that a gene window contains several heterozygous sites does not mean those sites materially change splicing, chromatin, or expression predictions. Most of the time, some of those variants are just sitting there being molecular wallpaper.
The real trigger for phased reruns is more like this: could the haplotype structure change the answer? That is much more plausible when you have multiple nearby variants in the same regulatory element, splice region, exon, or promoter-enhancer context, because AlphaGenome’s whole point is that long-range sequence context can matter across the 1 Mb window.
So the rule is:
Yes, phase probably matters when you are asking about allele-specific splicing or expression, compound cis effects, multiple nearby motif hits, or a suspicious locus where a consensus sequence could create a chromosome that neither haplotype actually has.
No, phase is not automatically worth it just because a gene has multiple heterozygous sites somewhere in or around it. The docs explicitly note that many variants have little effect, and personal-genome prediction from sequence models is still imperfect enough that more elaborate inputs do not guarantee a better answer for every gene.
So the blunt version is:
multiple hets are a reason to consider phased reruns, not a reason to mandate them.
You phase when the question is cis-sensitive. You do not phase every gene just because the genome is, inconveniently, a genome.
For your workflow, the sane strategy is:
first-pass screen with reference/edited windows, then phased reruns for top loci where nearby het context could realistically alter the mechanism.