def genetic_modification_source(testapp, lab, award, source, gene):
    item = {
        'lab': lab['@id'],
        'award': award['@id'],
        'category': 'insertion',
        'introduced_gene': gene['@id'],
        'purpose': 'expression',
        'method': 'CRISPR',
        'reagents': [
            {
                'source': source['@id'],
                'identifier': 'sigma:ABC123'
            }
        ]
    }
    return testapp.post_json('/genetic_modification', item).json['@graph'][0]