Gene Combination Relationship
GET /api/genecombinations/420/relationships/genes?format=api
{
    "data": [
        {
            "type": "Gene",
            "id": "BBS2"
        },
        {
            "type": "Gene",
            "id": "BBS4"
        },
        {
            "type": "Gene",
            "id": "MKKS"
        }
    ]
}