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Aim: Thalassaemia is a good candidate disease for control by preventive genetic programmes in developing countries. Accurate population frequency data are needed for planning the control of thalassaemia in the high risk Guangdong Province of southern China. Methods: In total, 13 397 consecutive samples from five geographical areas of Guangdong Province were analysed for both hoematological and molecular parameters. Results: There was a high prevalence of carriers of α thalassaemia (8.53%), β thalassaemia (2.54%), and both α and β thalassaemia (0.26%). Overall, 11 .07% of the population in this area were heterozygous carriers of α and β thalassaemia. The mutation spectrum of α and β thalassaemia and its constitution were fully described in this area. This study reports the true prevalence of silent α thalassaemia in the southern China population for the first time. In addition, two novel mutations that give rise to α thalassaemia, one deletion resulting in β thalassaemia, and a rare deletion (- - THAI allele) previously unreported in mainland China were detected. The frequency of the most common mutation, the Southeast Asian type of deletion (- - SEA, accounting for 48.54% of all α thalassaemias) was similar to the total of two α+ tholassaemia deletions (-α3.7 and -α4.2, accounting for 47.49% of α thalassaemia). Conclusion: Both α and β thalassaemia are widely distributed in Guangdong Province of China. The knowledge gained in this study will enable the prolected number of pregnancies at risk to be estimated and a screening strategy for control of thalassaemia to be designed in this area. [ABSTRACT FROM AUTHOR]

Background: Colorectal cancer is the third most common cancer in the world, arising mostly from pre-existing adenomatous polyps (adenomas) of the large bowel. Patients with colorectal adenomas are at increased risk of colorectal cancer because of a high recurrence rate for adenomas. We followed a cohort of 1490 patients with rectal adenomas to determine whether recurrence might be related to pathologic characteristics of the initial adenomas.Methods: The patients were identified in Haining County, China, from 1977 through 1978 by means of examination with a 15-cm rigid sigmoidoscope. They were followed by endoscopic examination at years 2, 4, 6, 11, and 16 after their initial polypectomy. New adenomas in the rectum were identified in 280 patients in these follow-up examinations.Results: Statistically significant twofold to threefold elevated risks of metachronous (recurrent) adenomas were observed for patients who had more than two initial adenomas or whose most advanced initial adenoma was more than 1.0 cm in size, was of villous/tubulovillous type, or showed moderate to severe dysplasia. Much stronger associations were observed for advanced metachronous neoplasms, which are defined as cancers or adenomas with severe dysplasia, with multivariate adjusted relative risks (95% confidence interval) of 4.2 (1.8-9.9) for a large initial adenoma (>1.0 cm), 8.1 (4.2-15.6) for villous/tubulovillous architecture, and 14.4 (5.0-41.3) for severe dysplasia. In particular, patients who had a large (>1.0 cm) adenoma with severe dysplasia at baseline had a relative risk of 37 (7.8-174.7) of developing advanced metachronous neoplasms compared with patients who had small adenoma(s) with mild dysplasia.Conclusions: The risk of metachronous adenomas is closely related to the pathology of initial adenomas, thus allowing identification of a high-risk group of adenoma patients for close surveillance after their initial polypectomy. [ABSTRACT FROM AUTHOR]