GTP cyclohydrolase (GCH1) is rate limiting for tetrahydrobiopterin (BH4) synthesis, where BH4 is a cofactor for nitric oxide (NO) synthases and aromatic hydroxylases. GCH1 polymorphisms are implicated in the pathophysiology of pain, but have not been investigated in African populations. We examined GCH1 and pain in sickle cell anemia where GCH1 rs8007267 was a risk factor for pain crises in discovery (n = 228; odds ratio [OR] 2.26; P = 0.009) and replication (n = 513; OR 2.23; P = 0.004) cohorts. In vitro, cells from sickle cell anemia subjects homozygous for the risk allele produced higher BH4. In vivo physiological studies of traits likely to be modulated by GCH1 showed rs8007267 is associated with altered endothelial dependent blood flow in females with SCA (8.42% of variation; P = 0.002). The GCH1 pain association is attributable to an African haplotype with where its sickle cell anemia pain association is limited to females (OR 2.69; 95% CI 1.21–5.94; P = 0.01) and has the opposite directional association described in Europeans independent of global admixture. The presence of a GCH1 haplotype with high BH4 in populations of African ancestry could explain the association of rs8007267 with sickle cell anemia pain crises. The vascular effects of GCH1 and BH4 may also have broader implications for cardiovascular disease in populations of African ancestry.

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Background: Helicobacter pylori can induce gastric atrophy in humans, which in turn increases gastric cancer risk. Whether H. pylori and gastric atrophy also affect the risk of esophageal squamous cell carcinoma (ESCC), however, remains unresolved.Methods: We performed a nested case-control study within the prospective Alpha-Tocopherol, BetaCarotene Cancer Prevention Study to assess these relationships. The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study is composed of 29,133 Finnish male smokers, ages 50 to 69 years, who were recruited during [1985][1986][1987][1988]. Using baseline sera, we assessed H. pylori status (via immunoglobulin G antibodies against whole-cell and CagA antigens) and gastric atrophy status [via the biomarkers pepsinogen I (PGI) and pepsinogen II (PGII)] in 79 ESCC cases and 94 controls. Logistic regression with adjustment for age, date of blood draw, education, cigarette smoking, alcohol, body mass index, and fruit and vegetable intake was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI).Results: Gastric atrophy (PGI/PGII <4) was associated with ESCC (OR, 4.58; 95% CI, 2.00-10.48). There was no evidence for an association between H. pylori and ESCC (OR, 0.94; 95% CI, 0.40-2.24).Conclusions: These results could be explained by misclassification of H. pylori status due to serologic amnesia, ESCC risk being dependent on the functional consequences or interactions of H. pylori rather than the infection per se, gastric atrophy having a different histogenesis in ESCC without being primarily dependent on H. pylori acquisition, or a lack of statistical power to detect an effect.Impact: Validation of these results may warrant mechanistic studies to determine the route of association between gastric atrophy and ESCC. Cancer Epidemiol Biomarkers Prev; 19(8); 1966-75. ©2010 AACR.

Pepsinogens are a class of endopeptidases that are secreted by the gastric epithelium and released into the circulation. Low serum pepsinogen I (PGI) and low serum pepsinogen I/pepsinogen II ratio (PGI/II ratio) are markers of gastric fundic atrophy, and have recently been shown to be associated with increased risk of esophageal squamous cell carcinoma (ESCC). We conducted the current study to test whether these markers are also associated with esophageal squamous dysplasia (ESD), the precursor lesion of ESCC. We measured serum PGI and PGII, using enzymelinked immunosorbent assays, in 125 case subjects (patients with moderate or severe ESD) and 250 sex-matched control subjects (no ESD) selected from an endoscopic screening study in Linxian, China. We used conditional logistic regression models adjusted for age, smoking and place of residence to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs). Serum PGI showed no statistically significant association with ESD, whether analyzed as a dichotomous, ordinal (quartiles) or continuous variable. Lower serum PGI/II ratio, however, showed a dose-response association with increased risk of ESD, with an adjusted OR (95% CI) of 2.12 (1.08-4.18), comparing the lowest versus the highest quartile. The association between the lower serum PGI/II ratio and log OR of ESD was nearly linear, and the p-value for the continuous association was 0.03. Lower serum PGI/II ratio was linearly associated with higher risk of ESD. This result is consistent with recent findings that gastric atrophy may increase the risk of ESCC. Published 2008 Wiley-Liss, Inc. This article is a US Government work and, as such, is in the public domain in the United States of America.Key words: esophageal cancer; squamous dysplasia; pepsinogen; China Pepsinogen I (PGI) and pepsinogen II (PGII) are 2 classes of endopeptidases that are secreted by the gastric epithelium and can hydrolyze peptides in acid environments. 1 Some of the secreted molecules are released into the circulation and can be measured as serum PGI and serum PGII.Serum pepsinogen levels have been used as markers of gastric fundic atrophy. 2,3 As this atrophy progresses, serum PGI levels are reduced but serum PGII levels remain stable or are increased, which results in lower PGI levels and a lower serum pepsinogen I/ pepsinogen II ratio (PGI/II ratio). 3 Both low serum PGI and low serum PGI/II ratio have been used as markers for gastric fundic atrophy. 2,3 However, low serum PGI/II is usually a more accurate marker for this atrophy than PGI alone. 3 Serum pepsinogens can also predict gastric cancer risk. A large number of epidemiologic studies have shown that atrophy of gastric fundic mucosa, diagnosed histologically or by measuring serum pepsinogens, is associated with higher risk of gastric cancer. [4][5][6][7][8][9][10][11][12][13][14][15][16] Like the association with atrophy, some studies have suggested that the serum PGI/II ratio may be a stronger risk predictor of future gastric cancer risk than serum PGI alone. 5,10,11 The ...