. 2005 Aug 25;7(6):R1200–R1207. doi: 10.1186/ar1812

Table 2.

Linkage analysis of the PTPN22-1858T allele to rheumatoid factor-seropositive (RF⁺) rheumatoid arthritis (RA) using the transmission disequilibrium test (TDT)

Families	Transmission [% (n)]	P
TDT RA sample 1
TDT RA index cases (n = 100)	66 (55)	0.022
TDT RA index cases RF⁺(n = 81)	66 (47)	0.029
TDT RA index cases RF^-(n = 19)	63 (8)	0.48
TDT RA sample 2
TDT RA index cases (n = 100)	53 (57)	0.69
TDT RA index cases RF⁺(n = 76)	56 (43)	0.45
TDT RA index cases RF^-(n = 24)	43 (14)	0.59
All TDT RA families
All TDT RA index cases (n = 200)	59 (112)	0.059
All TDT RA index cases RF⁺(n = 157)	61 (90)	0.037
All TDT RA index cases RF^-(n = 43)	50 (22)	1

RF^-, seronegative for rheumatoid factor. Transmission, percentage of heterozygous 1858C/T parents transmitting the 1858T allele. The plan was to test the hypothesis for RF⁺RA; analysis for all RA and RF^-RA were provided for the discussion.