Table 1.

D Segment Frequencies. Observed counts and relative frequencies of individual D segment usage in the P and NP datasets.

	P sequences		NP sequences
	Obs.	Rel. freq.	Obs.	Rel. freq.
D1-1	133	0.020	2	0.006
D2-2	811	0.125	76	0.234
D3-3	498	0.077	26	0.080
D4-4	78	0.012	1	0.003
D5-5	192	0.030	8	0.025
D6-6	141	0.022	5	0.015
D1-7	99	0.015	3	0.009
D2-8	129	0.020	4	0.012
D3-9	246	0.038	6	0.018
D3-10	547	0.084	17	0.052
D5-12	144	0.022	3	0.009
D6-13	295	0.045	22	0.068
D1-14	56	0.009	3	0.009
D2-15	268	0.041	22	0.068
D3-16	313	0.048	17	0.052
D4-17	263	0.041	10	0.031
D6-19	425	0.065	14	0.043
D1-20	10	0.002	0	0.000
D2-21	184	0.028	8	0.025
D3-22	527	0.081	28	0.086
D4-23	94	0.014	4	0.012
D5-24	153	0.024	3	0.009
D6-25	26	0.004	0	0.000
D1-26	364	0.056	13	0.040
D7-27	101	0.016	7	0.022
D0-IR	72	0.011	5	0.015
D1-IR1	94	0.014	6	0.018
D1-OR15	11	0.002	1	0.003
D2-IR2	33	0.005	2	0.006
D2-OF15	88	0.014	6	0.018
D3-OR15	47	0.007	2	0.006
D4-OR15	30	0.005	0	0.000
D5-OR15	18	0.003	1	0.003
	6490		325