Abstrak: Studies over 5 decades have examined ABO blood groups and risk of pancreatic cancer in Western, Asian, and other populations, though no systematic review has been published. We studied data from 908 pancreatic cancer cases and 1,067 population controls collected during December 2006-January 2011 in urban Shanghai, China, and reviewed the literature for all studies of this association. Random-effects meta-analysis provided summary odds ratio estimates according to blood group and by populations endemic versus nonendemic for cytotoxin-associated gene A (CagA)-positive Helicobacter pylori. In our Shanghai study, versus group O, only ABO group A was associated with risk (odds ratio (OR) = 1.60, 95% confidence interval (CI): 1.27, 2.03). In 24 pooled studies, group A showed increased risk in both CagA-nonendemic and -endemic populations (ORpooled = 1.40, 95% CI: 1.32, 1.49). In nonendemic populations, groups B and AB were also associated with higher risk (OR = 1.38, 95% CI: 1.16, 1.64; and OR = 1.52, 95% CI: 1.24, 1.85, respectively). However, in CagA-endemic populations, groups B and AB were not associated with risk (OR = 1.05, 95% CI: 0.92, 1.19; and OR = 1.13, 95% CI: 0.92, 1.38, respectively). These population differences were significant. One explanation for contrasts in associations of blood groups B and AB between CagA-endemic and -nonendemic populations could involve gastric epithelial expression of A versus B antigens on colonization behaviors of CagA-positive and CagA-negative H. pylori strains.

Abstrak: In the present study, we evaluated whether childhood differences in body height between singletons and twins persist into adulthood. Data from the Medical Birth Register of Norway were linked with data from the Norwegian National Conscript Service. This study used data on the 457,999 males who were born alive and without physical anomalies in single or twin births in Norway during 1967-1984 and who were examined at the mandatory military conscription (age 18-20 years; 1985-2003). For sibling comparisons, the authors selected the 1,721 sibships of full brothers that included at least 1 male born in a single birth and at least 1 male born in a twin birth (4,520 persons, including 2,493 twins and 2,027 singletons). An analysis of the total study population using generalized estimating equations showed that the twins were 0.6 cm (95% confidence interval: 0.4, 0.7) shorter than were the singletons after adjustment for a series of background factors. The fixed-effects regression analysis of the sibships that included both twins and singletons showed that the twins were 0.9 cm (95% confidence interval: 0.6, 1.2) shorter than were their singleton brothers. The study suggests that male twins born in Norway during 1967-1984 were slightly shorter in early adulthood than were singletons.