Table 1

Clinical and HLA data of the investigated twin pairs. Patients with episodes of uveitis (^*) or peripheral arthritis (^†) are indicated

Concordant twins			Date of birth	Onset	HLA-A	HLA-B	HLA-C	HLA-DR
1.1	male	AS	1964	1993	2	27, 62	w2, w3	4, 13
1.2	male	AS	1964	1990	2	27, 62	w2, w3	4, 13
2.1^†	male	AS	1943	1966	31, 32	13, 27	w2, w6	7, 15
2.2	male	AS	1943	1969	31, 32	13, 27	w2, w6	7, 15
3.1^* ^†	male	AS	1927	1944	2, 11	27, 62	w1, w2	4, 9
3.2^* ^†	male	AS	1927	1947	2, 11	27, 62	w1, w2	4, 9
4.1^* ^†	female	AS	1949	1975	3	27	w1, w2	11, 13
4.2	female	AS	1949	1978	3	27	w1, w2	11, 13

Discordant twins
5.1	female	AS	1930	1952	3, 28	7, 27	w1, w7	4, 15
5.2	female	healthy	1930		3, 28	7, 27	w1, w7	4, 15
6.1	male	AS	1952	1975	2, 29	27, 44	w2	4, 16
6.2	male	healthy	1952		2, 29	27, 44	w2	4, 16
7.1^†	male	AS	1942	1976	2, 26	27, 44	w2, w3	11, 15
7.2	male	healthy	1942		2, 26	27, 44	w2, w3	11, 15
8.1^†	female	AS	1947	1980	3	13, 44	w5, w6	1, 3
8.2	female	healthy	1947		3	13, 44	w5, w6	1, 3
9.1	female	USpA	1930	1969	1, 2	8, 27	w2, w7	1, 7
9.2	female	healthy	1930		1, 2	8, 27	w2, w7	1, 7
10.1	female	USpA	1964	1991	2	27, 35	w2, w4	4, 16
10.2	female	healthy	1964		2	27, 35	w2, w4	4, 16
11.1	female	AS	1959	1976	2	51	w7	11, 13
11.2	female	healthy	1959		2	51	w7	11, 13

Healthy twins
12.1	female	healthy	1969		11, 26	8, 55	w3, w7	3, 13
12.2	female	healthy	1969		11, 26	8, 55	w3, w7	3, 13
13.1	male	healthy	1964		2, 25	44, 62	w3, w5	1, 4
13.2	male	healthy	1964		2, 25	44, 62	w3, w5	1, 4