Available parameters and response documentation is available here

GET /lookup/rs113488022/hg38?add-varsome-user-entries=1
HTTP 200 OK
Allow: GET, HEAD, OPTIONS
Content-Type: application/json ;utf-8
ETag: "f9bd85acf59c0870738e8365d1440f80a65c89ccdec723f5e1c401cdc80cb92d"
Vary: Accept

[
  {
    "chromosome": "chr7",
    "alt": "C",
    "ref": "A",
    "pos": 140753336,
    "variant_id": "10380071407533360002",
    "variant_type": "SNV",
    "cytobands": "7q34",
    "publication_counts": null
  },
  {
    "chromosome": "chr7",
    "alt": "G",
    "ref": "A",
    "pos": 140753336,
    "variant_id": "10380071407533360003",
    "variant_type": "SNV",
    "cytobands": "7q34",
    "publication_counts": null
  },
  {
    "chromosome": "chr7",
    "alt": "T",
    "ref": "A",
    "pos": 140753336,
    "variant_id": "10380071407533360004",
    "variant_type": "SNV",
    "cytobands": "7q34",
    "publication_counts": null
  }
]