Table 1.

Success Rate and Chromosomal Specificity of Markers

Source	Markers	Failed	1st rate	2nd rate	Chr6	Spec(%)
MRC-L0 (RsaI)	93	57	31	5	29	93.55
MRC-L1 (SspI)	36	11	23	2	19	82.61
SB1	472	240	208	24	97	46.63
SB 1+2	385	206	162	17	88	54.32
YAC	323	183	122	18	41	33.61
Gene	26	8	18	0	11	61.11
Totals	1335	705	564	66	285	50.53

Source refers to the source of sequences from which markers were designed (MRC-L0 and MRC-L1, chromosome 6-enriched plasmid libraries made and sequenced in this study; SB1, early chromosome 6-enriched plasmid library prepared at the Sanger Centre using purified chromosome 6 DNA supplied by Princeton University; SB1 +2, a mixture of sequences from SB1 and from a later library, again prepared at the Sanger Centre; sequences from SB1 and SB1 +2 were produced by the Sanger Centre and by Baylor. YAC, sub-clones of YACs from the chromosome 6 physical map, sub-cloned and sequenced at the Sanger Centre; Gene, gene sequences). Markers gives the number of markers for which PCR primers were made; Failed markers include those rejected after initial testing, or which failed to give useable mapping data; in most cases, this was because the marker sequence proved to be multicopy. 1st rate and 2nd rate are those which typed either well or poorly on the mapping panels. Chr6 and Spec(%) give the number and percentage, respectively, of 1st-rate markers which mapped to chromosome 6.