Text: Gene expression data were analysed using the ddCt method using GAPDH as housekeeping gene. Human samples were obtained and handled according to the UK Home Office regulations and local guidelines in the laboratories. In this study, either three or four iPSC lines from healthy controls and two lines from patients carrying the SOD1D90A mutation were used. 
Question: Extract all the strains mentioned in the above text and return None if there are no strains mentioned.