Fetal hemoglobin (HbF) is regulated as a multigenic trait. By genome-wide association study, we confirmed that HBS1L-MYB intergenic polymorphisms (HMIP) and BCL11A polymorphisms are highly associated with HbF in Chinese ␤-thalassemia heterozygotes. In this population, the variance in HbF resulting from the HMIP is 13.5%; that resulting from the BCL11A polymorphism is 6.4%.

No abstract

The hypothesis that protection of infants from exposure to infectious agents with delayed first exposure to one or more specific agents together contribute to the aetiology of childhood leukaemia, especially common acute lymphoblastic leukaemia (cALL), has substantial indirect support from descriptive epidemiology and case-control studies in developed Western countries. A case-control study of childhood leukaemia diagnosed at ages 2-14 years has now been conducted in Hong Kong. Cases (n=98) formed a consecutive series of Chinese children diagnosed with acute leukaemia; controls (n=228) were identified following a survey using random digit dialling and required to attend for medical examination by a paediatrician. Interviews with mothers were conducted in hospital by one trained interviewer using a structured questionnaire. Odds ratios (OR) and 95% confidence intervals (CI) are reported for exposure variables capable of serving as proxies for exposure to infection in two critical time periods: first year of life, year before reference date (diagnosis for cases, corresponding date for controls). Analyses used logistic regression with adjustment for appropriate confounders. Change of area of residence reduced risk if during the first time period (OR = 0.47 [95% CI 0.23, 0.98]) and increased risk if during the second (OR=3.92, [95% CI 1.47, 10.46]). Reported roseola and/or fever and rash in the first year of life reduced risk (OR=0.33 [95% CI 0.16, 0.68]) whereas tonsillitis in the period 3-12 months before reference date increased risk (OR=2.56 [95% CI 1.22, 5.38]). Some other proxies for exposure to infection at the critical times were associated with predicted patterns of risk but day-care attendance failed to show predicted associations. These results provide support for the delayed exposure hypothesis in an affluent geographical setting in which population exposure to infectious agents is quite distinct from the settings of previous case-control studies.

Summary Incidence data of childhood leukaemia (CL) in Hong Kong (1 984-90) have been analysed for evidence of variation between small areas. All cases (n=261) were classified by morphological cell type, with the majority (n=205) being acute lymphoblastic leukaemia (ALL), and haematological review has permitted immunophenotypic classification for 73% of these. The data have been examined for evidence of spatial clustering within small census areas (TPUs) and for association with population mixing, with attention focused on those subgroups (especially the childhood peak of ALL -taken here to be diagnoses in children from 24 months up to the seventh birthday -and common ALL) which, it has been hypothesized, may be caused by unusual patterns of exposure and response to common infections. For the whole of Hong Kong, there was evidence of spatial clustering of ALL at ages 0-4 years (P = 0.09) and in the childhood peak (P<0.05). When these analyses were restricted to TPUs where extreme population mixing may have occurred, overall incidence was elevated and significant evidence of clustering was found for ALL (P<0.007) at these ages and for the common ALL in the childhood peak (P= 0.032). Replication of the analyses for subsets of leukaemia that were not dominated by the childhood peak of ALL found no evidence of clustering. This is the first investigation of an association between population mixing and childhood leukaemia in Asia and the first to include clustering and to consider particular subsets. The results are supportive of the 'infectious' aetiology hypothesis for subsets of childhood leukaemia, specifically common ALL in the childhood peak.

Severe oral mucositis is a common cause of morbidity in pediatric and adolescent patients undergoing chemotherapy. High-symptom burden due to mucositis may have profound impacts on patient quality of life and levels of psychological distress.