Disease Relationship
GET /api/diseases/325004/relationships/combination_set?format=api
{
    "data": [
        {
            "type": "Combination",
            "id": "OLI115"
        },
        {
            "type": "Combination",
            "id": "OLI116"
        },
        {
            "type": "Combination",
            "id": "OLI117"
        }
    ]
}