Table 1.

The number (#) of mirtrons derived from introns of different sizes.

Size of Intron	# of Mouse Mirtrons (489)	# of Human Mirtrons (479)
<100 bp	125	115
101–150 bp	52	49
151–250 bp	33	53
251–500 bp	60	57
501–1000 bp	70	68
1001–2500 bp	92	71
2501–5000 bp	27	47
5001–10,000 bp	19	13
10,001–50,000 bp	9	6
>50,000 bp	2	0