Table 1

The results of 14 laboratories on 78 samples

	Laboratories
	A	B	C	D	E	F	G	H	I	J	K	L	M	N
RP-PCR results
GGGGCC-repeat expansion
Yes	46	46	46	46	42	48	45	43	43	45	34	44	41	43
No	32	32	32	32	32	28	33	32	32	30	33	32	33	28
Q	0	0	0	0	4	2	0	3	3	3	11	2	4	7
False positive	0	0	0	0	0	2	0	0	0	2	1	0	0	0
False negative	0	0	0	0	1	0	1	0	0	0	2	0	1	0
Sensitivity (%)	100	100	100	100	91.3	100	97.8	93.5	93.5	93.5	71.7	95.7	89.1	93.5
Specificity (%)	100	100	100	100	96.8	87.5	100	100	100	93.8	96.9	100	100	87.5
Unclassified (%)	0	0	0	0	5.1	2.6	0	3.8	3.8	3.8	14.1	2.6	5.1	9.0
Amplicon-length analysis results
Numbers of amplicon
0	0	0	1	0	0	0	0	0	0	0	0	N.D.	N.D.	N.D.
1	54	54	55	56	56	54	54	51	56	54	51	N.D.	N.D.	N.D.
2	24	24	22	22	22	24	24	24	22	24	24	N.D.	N.D.	N.D.
Q	0	0	0	0	0	0	0	3	0	0	3	N.D.	N.D.	N.D.
RP-PCR+amplicon-length analysis results
GGGGCC-repeat expansion
Yes	46	46	46	46	46	48	45	43	43	43	34	44	41	43
No	32	32	32	32	32	29	33	32	32	30	34	32	33	28
Q	0	0	0	0	0	1	0	3	3	5	10	2	4	7
False positive	0	0	0	0	0	2	0	0	0	0	0	0	0	0
False negative	0	0	0	0	0	0	1	0	0	0	2	0	1	0
Sensitivity (%)	100	100	100	100	100	100	97.8	93.5	93.5	93.5	73.9	95.7	89.1	93.5
Specificity (%)	100	100	100	100	100	90.6	100	100	100	93.8	100	100	100	87.5
Unclassified (%)	0	0	0	0	0	1.3	0	3.8	3.8	6.4	12.8	2.6	5.1	9.0

No, sample numbers without large GGGGCC-repeat expansion; N.D., not determined; Q, sample numbers of undecided or unclassified samples Yes: sample numbers with large GGGGCC-repeat expansion.