def read_igor_D_gene_parameters(params_file_name):
    """Load genD from file.

    genD is a list of genomic D information. Each element is a list of the name
    of the D allele and the germline sequence.

    Parameters
    ----------
    params_file_name : str
        File name for a IGOR parameter file.

    Returns
    -------
    genD : list
        List of genomic D information.

    """
    with open(params_file_name, 'r') as params_file:
        D_gene_info = {}

        in_D_gene_sec = False
        for line in params_file:
            if line.startswith('#GeneChoice;D_gene;'):
                in_D_gene_sec = True
            elif in_D_gene_sec:
                if line[0] == '%':
                    split_line = line[1:].split(';')
                    D_gene_info[split_line[0]] = [split_line[1], int(split_line[2])]
                else:
                    break

    genD = [[]]*len(list(D_gene_info.keys()))

    for D_gene in list(D_gene_info.keys()):
        genD[D_gene_info[D_gene][1]] = [D_gene, D_gene_info[D_gene][0]]

    return genD