def get_threshold_from_DESC(desc_file):

    """
    Parses a family DESC file and returns the gathering
    threshold

    desc_file: The path to a valid Rfam family DESC file

    return: A string which is the corresponding gathering threshold
    """

    threshold = 0
    desc_fp = open(desc_file, 'r')

    for line in desc_fp:
        # look for the GA line
        if line[0:2] == 'GA':
            # extract threshold which after splitting
            # is the last element in the list
            threshold = line.strip().split(' ')[-1]

    return threshold