[Locations of crossover breakpoints within the CMT 1 A-REP repeat in patients with hereditary neuropathy with liability to pressure palsy--detection by recombinant chromosome-specific polymerase chain reaction].

: The crossover breakpoints for hereditary neuropathy with liability to pressure palsies (HNPP) are located in the CMT 1 A-REP repeat flanking a 1.5 Mb region of chromosome 17p11.2-12. Three-unrelated HNPP patients have breakpoints in a 3.2 kb novel fragment of recombinant chromosome in the CMT 1 A-REP repeat. The fragment is detected by recombinant chromosome-specific polymerase chain reaction (PCR). Further analysis of PCR demonstrated a 1.2 kb novel junction fragment in the 3.2 kb region in all HNPP patients. The precise mapping of the breakpoints indicated that 2 patients were localized in a 700 bp interval of the 1.2 kb fragment 1.3kb telomeric to a marier transposon-like element (Kiyosawa and Chance, HMG 5: 745-753, 1996), suggesting that this region is a recombinational "hotspot" within the CMT 1 A-REP repeat for HNPP as well as CMT 1 A.