Summary of the FISH results. Each case number (1-21) is indicated to the left. For clarity, the cases were ordered depending on their breakpoint location, allowing further assignment into two different groups (I and II; indicated to the right). The symbols used to designate the result of a FISH experiment are indicated at the bottom right of the figure. The approximate locations of the YAC clones used, in relation to selected markers and genes on the physical map, is based on the results reported by Chen et al, 1997,18 and public available databases (see Materials and Methods). TheCMT1A locus and SMS common deletion region, together with the repetitive sequence elements (CMT1A-REP, and SMS-REP) contained within these regions, are indicated below the physical map. At the bottom, an ideogram of chromosome 17 is depicted, showing the approximate location of the region investigated. *Case 7 showed a split signal using YAC 935a6, with one signal on each q arm (see results and Fig 2C). For abbreviations used, see text.