Frequency of recent retrotransposition events in the human factor IX gene

Two germline retrotransposition mutations of recent origin were observed in 727 independent mutations (0.28%) in the human factor IX gene (F9) of pati ents with hemophilia B: 1) a 279 bp insertion in exon H originating from an Alu family of short interspersed elements not previously known to be activ e and, 2) a 463 bp insertion in exon E of a LINE1 element originating in th e maternal grandmother. If the rates of recent germline mutation in F9 are typical of the genome, a retrotransposition event is estimated to occur som ewhere in the genome of about one in every 17 children born. Analysis of ot her estimates for retrotransposition frequency and overall mutation rates s uggests that the actual rate of retrotransposition is likely to be in the r ange of one in every 2.4 to 28 live births. Hum Mutat 17:511-519, 2001, (C) 2001 Wiley-Liss, Inc.