Table 1.

Characteristics of the clinical populations studied. Acute GVHD was diagnosed and graded according to standard criteria employed at the time of documented patient care. Note that the ratio of affected to unaffected individuals is not uniform across cohorts, primarily because the criteria for patient selection (which were defined prior to genetic analysis, and which for Cohorts B and C reflected the design of earlier studies) differed from institution to institution; for example, Cohort C utilized a cohort design, while Cohort B utilized a case/control design and over-sampled patients with severe acute GVHD to maximize power. Diagnostic sensitivity in the grading of GVHD can also differ between clinical institutions ³³ though it is generally well-harmonized within institutions.

	Cohort A (initial screen)		Cohort B	Cohort C
	A1	A2
Hospital	Helsinki University Central Hospital	Dana-Farber Cancer Institute	Various	Fred Hutchinson Cancer Research Center
Pre-transplant conditioning	Myeloablative	Myeloablative	Myeloablative	Myeloablative
Transplant year	1993–2005	1995–2005	1985–1993	1992–2004
Donor type	HLA-identical sibling	HLA-identical sibling	HLA-identical sibling	HLA-identical sibling
Donor/recipient pairs	232	182	336	595
Graft type
Bone marrow	77	36	336	265
Peripheral blood stem cells	155	146	0	226
Both	0	0	0	4
Donor/patient sex
Female/male	50	45	74	164
Female/female	57	46	86	115
Male/male	66	51	90	203
Male/female	59	40	86	113
Acute GVHD (grade II–IV)
Yes	39	54	243	410
No	193	128	93	180
Not gradable	0	0	0	5
Disease
Non-malignant disease	7	8	0	0
Malignant hematological disease	225	174	0	595
N/A	0	0	336	0