Available parameters and response documentation is available here

GET /lookup/rs113488022?format=api
HTTP 200 OK
Allow: GET, HEAD, OPTIONS
Content-Type: application/json ;utf-8
ETag: "4d82be7d5eeb125367c6e975dc46a1a4e62d9be99d8931516d717f2928633d8e"
Vary: Accept

[
  {
    "chromosome": "chr7",
    "alt": "C",
    "ref": "A",
    "pos": 140453136,
    "variant_id": "10190071404531360002",
    "variant_type": "SNV",
    "cytobands": "7q34",
    "publication_counts": null
  },
  {
    "chromosome": "chr7",
    "alt": "G",
    "ref": "A",
    "pos": 140453136,
    "variant_id": "10190071404531360003",
    "variant_type": "SNV",
    "cytobands": "7q34",
    "publication_counts": null
  },
  {
    "chromosome": "chr7",
    "alt": "T",
    "ref": "A",
    "pos": 140453136,
    "variant_id": "10190071404531360004",
    "variant_type": "SNV",
    "cytobands": "7q34",
    "publication_counts": null
  }
]