PULSED-FIELD ANALYSIS OF HPRT T-CELL LARGE DELETIONS - TELOMERIC REGION BREAKPOINT SPECTRUM

In order to determine a large deletion breakpoint spectrum, 25 indepen dent hprt T-lymphocyte mutants with deletions extending from hprt into the telomeric or centromeric flanking chromosomal region were analyze d by pursed field gel electrophoresis (PFGE). PFGE was used to determi ne deletion sizes which allowed localization of breakpoints external t o hprt to specific chromosomal positions in mutants containing an intr a-hprt breakpoint. A breakpoint spectrum based on 19 large deletion mu tants is reported for the Xq26 chromosomal region telomeric to hprt. A potential cluster of breakpoints (4/19) was observed approximately 60 kb from hprt. In addition, maximum recoverable deletion size was at l east 3.5 Mb. Three of the 25 mutants analyzed appeared to be complex d eletion events.