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: "3a0d6cfbd9a2ee26fd8fa831666ac24a65ed83d31c921ce5e7db60464f945753"
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
  }
]