def get_clonotype_vdj_pair(sequence_ids, clonotype_tuple, vdj_gene_pairs):
    """Get the VDJ gene pair associated with the clonotype.
    If the gene pair is not in vdj_gene_pairs, it will return None.
    """
    genes = set([sequence_ids[seq].split('_')[0] for seq in list(clonotype_tuple)])
    genes = tuple(sorted(list(genes)))

    return vdj_gene_pairs.get(genes, None)