Genetics of Duodenal and Gastric Ulcer

Peptic ulcer disease

Peptic ulcer disease had a tremendous effect on morbidity and mortality until the last decades of the 20th century, when epidemiological trends started to point to an impressive fall in its incidence. Two important developments are associated with the decrease in rates of peptic ulcer disease: the discovery of effective and potent acid suppressants, and of Helicobacter pylori. With the discovery of H pylori infection, the causes, pathogenesis, and treatment of peptic ulcer disease have been rewritten. We focus on this revolution of understanding and management of peptic ulcer disease over the past 25 years. Despite substantial advances, this disease remains an important clinical problem, largely because of the increasingly widespread use of non-steroidal anti-inflammatory drugs (NSAIDs) and low-dose aspirin. We discuss the role of these agents in the causes of ulcer disease and therapeutic and preventive strategies for drug-induced ulcers. The rare but increasingly problematic H pylori-negative NSAID-negative ulcer is also examined.

Epidemiology and genetics of peptic ulcer

At the turn of the century, duodenal ulcer rose from rarity to affect 10% of males in their life time, subsequently declining in some countries such as UK, levelling off in others such as Germany, and continuing to increase in still others such as Hong Kong. The annual incidence per 1000 population varies from about 1 in Japan to 1.5 in Norway, 1.8 in USA and 2.7 in Scotland, and the frequency also varies within many individual countries, such as Australia, China and India, and among races such as a higher prevalence among whites than blacks in USA and among Chinese than Javanese in Indonesia. Ulcer frequency is higher in winter months, and this appears universal, being true in cold as well as in warm countries. Most places report a rise of ulcer rates among the elderly in recent decades. The male to female ratio also varies geographically, for example from 1:1 in USA to 18:1 in India, and with time such as moving from 2:1 to 1:1 in the last two decades in USA, and the duodenal ulcer to gastric ulcer ratio varies widely from place to place, for example from 0.8 in Japan to 19:1 in Africa and 32:1 in India. Placebo healing rates also differ geographically, ranging from 5% in Philippines to 78% in Mexico. These epidemiological data can only be explained by the presence of multiple aetiological factors, including analgesics, society stress, cigarette smoking, Helicobacter pylori, dietary factors, and genetic factors. Three lines of evidence support a genetic role: family studies, twin studies and blood group studies. Family aggregation occurs more commonly in patients with early-onset (< 30 yr) of symptoms. Blood group O prevalence is more associated with late-onset of symptoms. Other genetic markers include nonsecretor status, HLA antigens, phenylthiocarbamide taste sensitivity, and alpha-1-antitrypsin. Genetic syndromes such as MEN I also support a genetic role and give insight into pathogenetic mechanisms. The best physiological marker is still hyperpepsinogenemia I, which is transmitted by autosomal dominance, despite recent report of lower serum pepsinogen 1 after healing of Helicobacter pylori associated gastritis.

Characteristics of teen-age patients with juvenile duodenal ulcer. Relation between inherited hyperpepsinogenemia I and duodenal ulcer

We analyzed environmental factors, family history of peptic ulcer, gastric acid secretion, and serum levels of pepsinogen I (PG I) and gastrin in 56 juvenile patients with duodenal ulcer and 39 normal teenage subjects. Basal acid output and maximal acid output were significantly higher in our duodenal ulcer patients than in controls without ulcer (both, p < 0.01), and patients with duodenal ulcer showed significantly higher serum levels of PG I and gastrin than the controls (both, p < 0.001). There were no significant differences in any environmental factor between the patients and controls. Fifteen of the 17 patients who had one or both parents with hyperpepsinogenemia I had high serum PG I levels. Over half of the duodenal ulcer patients had high serum gastrin levels, irrespective of family history of hypergastrinemia. Our findings suggest that hyperpepsinogenemia I and hypergastrinemia are important characteristics and that genetic background, particularly the inheritance of a gastric mucosal trait expressed as hyperpepsinogenemia I, is frequently involved in the pathogenesis of juvenile duodenal ulcer.

Chronic antral gastritis, Lewis(a+) phenotype, and male sex as factors in predicting coexisting duodenal ulcer

Chronic antral gastritis, Lewis(a+) phenotype (Le(a+)), and male sex are common in patients with peptic ulcer. To approximate the relative risks (RR) and possible interactions of these factors in predicting coexisting active duodenal (DU) or gastric ulcer (GU), a consecutive endoscopic series of 140 ulcer patients and 215 non-ulcer controls was examined. The Lea phenotype (Le(a+) versus Le(a-)) was determined immunohistochemically as binding of Le(a)+-specific monoclonal antibody to surface epithelial secretory mucosubstances in gastric biopsy specimens. The presence versus absence of the gastritis was determined histologically from antral specimens. The RRs of the factors in the prediction of ulcer were approximated as age-adjusted RRs when the risk of ulcer in the absence of the factors--that is, in the absence of gastritis, in female sex and in Le(a-) phenotype--was applied as a base line (RR = 1). A case-control design, logistic linear modelling, and the maximal likelihood method were used in estimation of the risks. The RR of coexisting distal ulcer (DU or pyloric or prepyloric GU) was increased in the presence of gastritis (RR = 10.2), in male sex (RR = 3.0), and in Le(a+) phenotype (RR = 1.8). The RR of proximal ulcer (angular or corpus GU) was increased in the presence of gastritis (RR = 35) but decreased in the presence of male sex (RR = 0.5) and Le(a+) phenotype (RR = 0.7). As predictors of both distal and proximal ulcer, gastritis, sex, and Le(a) phenotype were independent of each other; that is, their joint value in prediction of ulcer is a multiplicand of the marginal risks. Thus, a 50-fold difference in the joint RR could be approximated between the extreme risk groups for distal ulcer--that is, between Le(a+) males with gastritis and Le(-a) females with normal antrum. In a consecutive series of outpatient endoscopies, 45% of females and 8% of males could be categorized to these extreme 'low'- and 'high'-risk groups, respectively. We conclude that sex, Le(a) phenotype, and gastritis are factors that, at least in ordinary outpatient endoscopy material, divide subjects to subgroups with very different risks and probabilities for having coexisting peptic ulcer.

The genetics of peptic ulcer

Non-malignant ulceration of the stomach and duodenum was, until relatively recently, considered to be one disease and was known by the all-embracing term peptic ulcer. Evidence from several sources tends to support the idea that even the broad divisions of gastric and duodenal ulcer may themselves be the end results of multiple separate disease processes. Genetic studies have helped considerably in the characterisation of these individual conditions.

Study of duodenal ulcer disease in 100 families using total serum pepsinogen as a genetic marker

Although various markers have been used in attempts to elucidate the mode of inheritance of duodenal ulcer, they have not significantly contributed to a clear understanding of the problem. In the present study total serum pepsinogen was used as a genetic marker and its concentrations were estimated in 100 ulcer patients and their family members up to three generations. Eighty three per cent of the ulcer patients had hyperpepsinogenaemia on a familial basis, and it followed an autosomal dominant mode of inheritance. Thus a large majority of ulcer patients have associated hyperpepsinogenaemia which forms a genetic basis of their disease. The remaining 17% ulcer patients did not have associated hyperpepsinogenaemia nor was the ulcer inherited by the family. Based on these observations we wish to suggest that duodenal ulcer associated with hyperpepsinogenaemia may be considered a genetic disease. This type may be termed 'primary duodenal ulcer'. In the remaining patients without hyperpepsinogenaemia or affected relatives the ulcer may be called 'secondary duodenal ulcer'. Thus total serum pepsinogen may be considered a reliable genetic marker in helping to delineate the genetic disorder from the non-genetic, thereby improving the predictive ability in duodenal ulcer.

Genetic and evolutionary implications in peptic ulcer disease

The evidence for a genetic component in peptic ulcer disease has been based on twin, family, and blood group studies. A polygenic model for the inheritance of peptic ulcers has been displaced by a genetic heterogeneity model based on several lines of evidence, some of the most powerful being recent work using subclinical markers. One marker in particular, an elevated level of serum pepsinogen I (PG I), a pepsin precursor produced by the gastric mucosa, secreted into the stomach lumen and also appearing in the bloodstream, has been found to be associated with a subgroup of duodenal ulcer patients. Segregation analysis of elevated serum PG I in duodenal ulcer sibships demonstrates familial aggregation consistent with autosomal dominant inheritance. Elevated PG I is also accompanied by gastric hyperacidity and presumably indicates those individuals with an increased mass of chief and parietal cells, and thus an increased capacity for peptic activity, an important element in the pathogenesis of ulcer disease. An evolutionary hypothesis based on selection for peptic activity and acidity is offered to explain several of the epidemiologic and genetic elements of this group of chronic diseases.

Gastric and duodenal ulcer are each many different diseases

It is becoming increasingly apparent that peptic ulcer is not one disease, but a genetically, etiologically, and pathogenetically heterogeneous group of diseases that share a common endpoint, an ulcer crater in those parts of the gastrointestinal tract exposed to acid and pepsin. The evidence that both gastric and duodenal ulcer are each many different diseases is reviewed and a classification of the peptic diseases is proposed. The implication of this extensive heterogeneity is that each of the disorders leading to peptic ulcer may have a distinct etiology, pathophysiology, genetics, and natural history, and thus may be amenable to different modes of therapy and prevention. Only through the complete delineation of each of the disorders leading to peptic ulcer will specific diagnosis, prognosis, and treatment be possible for peptic ulcer patients and their families.

HLA and duodenal ulcer

One hundred and one white patients, consisting of 78 men and 23 women, with duodenal ulcer were HLA typed. An association was found between duodenal ulcer and HLA-B12.