Available parameters and response documentation is available here

GET /lookup/chr19:20082943:1:G
HTTP 200 OK
Allow: GET, HEAD, OPTIONS
Content-Type: application/json ;utf-8
ETag: "0623417061cc2d16c7fa5d3ef0faaeb4e141e0524c7a69168b6a5de065c9a7df"
Vary: Accept

{
  "chromosome": "chr19",
  "alt": "G",
  "ref": "T",
  "pos": 20082943,
  "variant_id": "10190190200829430003",
  "variant_type": "SNV",
  "cytobands": "19p12",
  "publications": {
    "publications": [],
    "genes": []
  }
}