Imprinted genes show unique patterns of sequence conservation

BMC Genomics

Table 2 Features of different PCS classes in human

group	number of PCSs	conser-vation score	length (bp)	G+C content	PCSs with ≥ 1 CpG	CpGobs/CpGexp of PCSs with ≥ 1 CpG	(TpG+CpA)/(2·CpG) ratio of PCSs with ≥ 1 CpG
overlapping with CpG islands
imprinted	321	392	69	65.93%	94.38%	0.79	0.73
maternal	170	417	75	66.48%	95.29%	0.85^a	0.59
paternal	151	379	62	65.44%	92.72%	0.74*	0.83*
autosomal	55931	385	58	67.48%	95.30%	0.83	0.68
intronic
imprinted	1120	320*	40	38.89%****	32.05%***	0.51****	2.50*****
maternal	719	320	41	39.39%****	33.38%***	0.52**	2.50*****
paternal	401	320	40	38.10%**	29.68%	0.50**	2.50****
autosomal	365258	329	40	36.54%	25.42%	0.42	3.83
intergenic
imprinted	1787	325****	40****	39.04%*****	33.97%***	0.47****	2.83*****
maternal	832	320****	39***	35.78%^c	25.00%^b	0.53****^a	3.00****
paternal	955	329***	41	42.31%***	41.78%***	0.45*	2.50*****
autosomal	588309	338	43	36.36%	27.32%	0.42	4.00
unique
imprinted	2357	325****	39****	38.46%*****	29.87%***	0.45****	3.00*****
maternal	1304	320*****	39****	36.72%^c	25.61%^b	0.46****	3.00*****
paternal	1053	329***	40	40.74%*****	35.14%***	0.44	3.00*****
autosomal	844703	338	42	36.36%	25.49%	0.39	4.33

* p < 0.01, ** p < 0.005, *** p < 0.001, **** p < 1e^-4, ***** p < 1e^-10 for comparison with autosomal PCSs (χ² test for fractions of PCSs, Wilcoxon test for all other features). If maternally and paternally expressed genes differ significantly from each other, this is indicated as following: ^a p < 0.05, ^b p < 0.005, ^c p < 1e^-4
Unique PCSs do not overlap with protein encoding exons, repetitive elements, or CpG islands. The shown absolute numbers of PCSs are not normalized by the lengths of the analyzed genomic segments. Hence they give information about the amount of available data but not about frequencies or coverage of PCSs in the listed genomic segments.

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