MGI alleles without genomic position

[pnrobinson]

the anx allele (http://www.informatics.jax.org/allele/MGI:1856657) is a locus for which the actual genetic variant is not known. When you go from https://beta.monarchinitiative.org/variant/MGI:1856657 to the gene page, the gene page is empty: https://beta.monarchinitiative.org/variant/MGI:1856657#gene

Probably we want to filter the alleles in MGI according to whether they are associated with a gene or not and adjust the behavior of our UI. There is code in phenol that filters out genetic markers that are not associated with genes that could be used as a basis.