Data source: Load Geisinger phewas data

[andrewsu]

This paper https://www.sciencedirect.com/science/article/pii/S0002929718300624 describes another PheWAS study (similar to the one loaded in #66). Data are in Table S2 -- 1118 associations between SNV/SNPs and ICD-9 codes.

This can probably be added as an additional data source for https://pending.biothings.io/phewas. Can change the existing key to "VUMC" and then add this new data under a key "geisinger"...