def METHOD_NAME(self, chrom, start, ref, alt, assembly, dataset):
    # Initialzie output
    out = {'datasetId': dataset, 'exists': False}
    q_type = 'snp'
    # verify information and build query string
    if dataset in self.pos_dbs + self.assembly_dbs:
        if chrom and start and alt and assembly in self.assembly_keys:
            assembly = self.assembly_keys[assembly]  # get hg assembly notation
            if alt[:3] == 'DEL':  # syntax: "alternateBases": "DEL85689"
                q_type = 'del'
                ref = ''
            elif alt[:3] == 'DUP':  # "alternateBases": "DUP85689"
                q_type = 'dup'
                ref = ''
            elif not ref:
                q_type = 'ins'
                ref = ''
            q = self.format_query_string(q_type, chrom, start, ref, alt, assembly, dataset)
            # perform query and format result
            # for now always search against hg19 index...
            res = self.web_settings.es_client.search(
                index=self.web_settings.ES_INDICES[assembly],
                body={"query": {"query_string": {"query": q}}},
                _source=[dataset]
            )
            res = self.result_transform.transform(res, dotdict(dotfield=True))
            if res and res.get('total') > 0:
                out = self.format_output(res, out, q_type)
    return out