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Background and aims: We adopted the twin method to disentangle the genetic and environmental components of susceptibility to coeliac disease (CD). We estimated disease concordance rate by zygosity and HLA genotypes, discordance times, progression rates to disease, and heritability. Methods: We crosslinked the Italian Twin Registry with the membership lists of the Italian Coeliac Disease Association and recruited 23 monozygotic (MZ) and 50 dizygotic (DZ) twin pairs with at least one affected member. Zygosity was assigned by DNA fingerprinting, and HLA-DQ and DR alleles were genotyped. Disease status was ascertained by antiendomysial, anti-human tissue transglutaminase antibodies, and bowel biopsy. Results: Concordance was significantly higher in MZ (83.3% probandwise, 71.4% pairwise) than in DZ (16.7% probandwise, 9.1% pairwise) pairs. Concordance was not affected by sex or HLA genotype of the co-twin and being MZ was significantly associated with the occurrence of CD (Cox adjusted hazard ratio 14.3 (95% confidence interval 4.0–50.3)). In 90% of concordant pairs the discordance time was ⩽2 years. MZ and DZ co-twins had 70% and 9% cumulative probability of having symptomatic or silent forms of CD, respectively, within five years. Under ACE (additive genetic, common, and unshared environmental factors) models, with CD population prevalences of 1/91 and 1/1000, heritability estimates were 87% and 57%, respectively. Conclusion: MZ pairs have a high probability of being concordant, regardless of sex or HLA genotype. Most of the affected co-twins receive a diagnosis within two years. A remarkable proportion of phenotypic variance is due to genetic factors.

Background: In a previous hospital based study, we suggested that undiagnosed coeliac disease has a prevalence, among pregnant women, of 1:80, and is a cause of unfavourable outcome of pregnancy. Aims: In order to confirm or dismiss this hypothesis, which has significant public health implications, we carried out a large population based study on a stratified sample from the whole Campania region. Patients: During the period of the study, 5345 women were admitted to the OBS-GYN wards regional network: 5055 (95%) were enrolled in the study. Methods: Antihuman IgA class antitissue transglutaminase (TGASE) antibodies were tested by an ELISA method. Endomysial antibodies (EMA) were investigated on thin sections of human cord blood by an immunofluorescence test. The HLA class II DQA1*0501/DQB1*02 and DQA1*0301/DQB1*0302 haplotypes were assessed using the Eurospital Eu-DQ kit. Duodenal biopsy was not considered feasible by the ethics committee for pregnant women near delivery. Results: Fifty one of 5055 patients had confirmed positive results. We added to these 12 women with known coeliac disease, giving a prevalence rate for coeliac disease of 1:80 (exactly the value observed during the first study). Comparing the 51 TGASE positive with 4997 negative women, we did not observe an excess risk of abortion, premature delivery, small birth weight, or intrauterine growth retardation. Anaemia was more frequent in cases than controls. Conclusions: Undiagnosed coeliac disease is frequent among pregnant women (>1%) but is not associated with an unfavourable outcome of pregnancy.

The primary adult type hypolactasia is the most common form of genetically determined disaccharidase deficiency. This study examined a large and homogeneous population of the south of Italy: surgical biopsy specimens of proximal jejunum from 178 adult subjects have been assayed for disaccharidase activities; the expression of lactase protein and lactase activity has also been investigated on tissue sections by immunomorphological and enzymohistochemical techniques. Histograms of lactase to sucrase ratio were found to provide a useful distribution of the lactase activity; a lactase to sucrase ratio of 0.17 was found to show discrimination between tissues with persistence of high lactase activity and tissues with adult type hypolactasia. In all 28 subjects with persistent high lactase activity, a uniform distribution of lactase protein and lactase activity in all villus enterocytes was detected, whereas in all 150 subjects with adult type hypolactasia a variable number of villus enterocytes failed to express the lactase. Moreover in hypolactasic samples the lactase activity on tissue sections was constantly detected later than in samples with persistent high lactase activity. The absolute correlation between the immunohistochemical and enzymohistochemical features and the assessment of lactase activity in intestinal homogenates suggests that the morphological criteria are an alternative method for the diagnosis of adult type hypolactasia in human biopsy specimens from proximal small jejunum.