Table 1. Intrastrand and interstrand G-quadruplex sequences by human chromosome.

Chromosome	Unique interstrand		Intrastrand		Intra/inter
	count	per MB	count	per MB	ratio
Genome wide	550,977	177.98	374,834	121.08	0.68
chr1	48,860	196.03	32,597	130.78	0.67
chr2	39,032	160.49	26,826	110.30	0.69
chr3	26,696	134.81	18,839	95.14	0.71
chr4	21,369	111.79	15,358	80.34	0.72
chr5	24,701	136.53	17,587	97.21	0.71
chr6	22,788	133.17	16,675	97.45	0.73
chr7	28,578	179.58	19,372	121.73	0.68
chr8	22,872	156.27	15,750	107.61	0.69
chr9	26,855	190.17	17,522	124.08	0.65
chr10	26,533	195.77	17,420	128.53	0.66
chr11	30,587	226.56	19,984	148.02	0.65
chr12	23,132	172.82	16,330	122.00	0.71
chr13	11,244	97.63	7,802	67.74	0.69
chr14	17,177	160.01	11,311	105.37	0.66
chr15	17,585	171.51	11,733	114.43	0.67
chr16	25,607	283.41	16,495	182.56	0.64
chr17	29,171	359.27	18,897	232.74	0.65
chr18	10,458	133.94	7,474	95.73	0.71
chr19	30,206	510.85	20,794	351.67	0.69
chr20	17,655	280.12	11,496	182.40	0.65
chr21	7,857	163.25	4,848	100.73	0.62
chr22	18,280	356.30	10,420	203.10	0.57
chrX	20,295	130.71	16,468	106.06	0.81
chrY	3,436	57.87	2,832	47.70	0.82

For each chromosome in the human nuclear genome (v. hg19), the numbers of intrastrand and interstrand potentially quadruplex-forming sequences are listed. Sequences with loops up to 7nt long and at least three guanines per tract are considered. In case of overlapping interstrand quadruplexes, only one is taken into account (unique DS-PQS).