Table 2.

Familial risks of concordant pernicious anemia.

Proband	O	SIR	95% CI		O	SIR	95% CI		O	SIR	95% CI
	All				Women				Men
First-degree relative	250	3.88	3.41	4.39	127	3.58	2.98	4.26	123	4.24	3.53	5.06
	Parents only				Sibling only				Both parent and sibling
Parent/sibling	175	3.08	2.64	3.57	101	6.43	5.24	7.82	2	6.64	0.63	24.43

Bold type: 95% CI does not include 1.00. O = observed number of cases; SIR = standardized incidence ratio; CI = confidence interval.