Table 1.

Amino acid differences among the eight most common HLA-B27 allotypes

	Amino acid position
	47a	59	60a	67b	77	80	81	82	83	97	113	114	116	131	152	164	211
B*27:05	P	Y	W	C	D	T	L	L	R	N	Y	H	D	S	V	C	A
B*27:02					N	I	A
B*27:03		H
B*27:04					S										E		G
B*27:06					S							D	Y		E		G
B*27:07										S	H	N	Y	R
B*27:08					S	N		R	G
B*27:09													H

^a Positions 47 and 60 are located in the loop surrounding Cys-67. Mutations at these positions are expected to affect homodimer formation.

^b Key cysteine residue involved in the formation of homodimers.