Table 4. Genomic features with significant differences in their distributions between Alu insert-containing versus insert-free windows.

Genomic feature	Medians of the Integration windows	Medians of the Non-Integration windows	Absolute difference in medians	Z-value	p-values of the Mann-Whitney-Wilcoxon test
Gene content	0.3027	0.2164	0.0863	5.75	<0.0001a
SINE content	687.5	523	164.5	6.14	<0.0001a
GC content	0.4125	0.3984	0.0141	4.49	<0.0001a
Most conserved element densityb	785.5	750	35.5	3.01	0.0013a
Genome instability 13-mer frequencyc	55	42	13	5.34	<0.0001a

^a: Testing the hypothesis that Alu insert-containing windows have a right-tailed distribution compared with insert-free windows.

^b: Most conserved elements density as defined in [46].

^c: The frequency of the CCNCCNTNNCCNC motif associated with crossover events at recombination hotspots. They cluster at non-allelic homologous recombination (NAHR) breakpoints and mitochondrial deletion hot spots [50].