def read_dysplasia_mappings(mappings):
	"""
	Read dysplasia mappings stored within file

	Params:
		mappings (str): path to dysplasia mappings file

	Returns: a dict of {trigger: grade} representing mappings for each use-case
	"""

	with open(mappings, 'r') as file:
		lines = file.readlines()

	mappings = {'colon': {}, 'cervix': {}, 'celiac': {}, 'lung': {}}
	for line in lines:
		trigger, grade, use_cases = line.strip().split('\t')
		use_cases = use_cases.split(',')
		for use_case in use_cases:
			mappings[use_case][trigger] = grade.split(',')
	return mappings