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: "6a0a750066a51f6d508019e1240db8f6e6022c51ec4be0e18a1a2350bc16319c"
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
  }
]