Sequence coordinates of FRT-derived deficiencies are based on the locations of progenitor insertions. In some cases locations are approximations based on sequence features stated to include a deficiency endpoint, such as 'within the first exon of transcript x'. Deleted-segment statements reflect the maximal potential extent of a deficiency based on available breakpoint information. Depending on the type of breakpoint information available, deleted segments may reflect observed cytology or cytological locations estimated from sequence coordinates.