BACKGROUND: The geographic mortality difference of Creutzfeldt-Jakob disease is still unclear in Japan.
METHODS: Using vital statistics of Japan for 6 year period between 1999 and 2004 officially published by the government, we observed the mortality from Creutzfeldt-Jakob disease (ICD-10th: A81.0 and A81.8) by prefecture. Standardized mortality ratios were calculated for the 47 prefectures.
RESULTS: For the observed 6 years, a total of 792 deaths from Creutzfeldt-Jakob disease were observed whole in Japan. Two prefectures, Akita and Yamanashi, presented significantly high standardized mortality ratios. In addition, Tochigi, Kochi, and Nagasaki showed standardized mortality rates higher than 1.5 without significance. No prefecture had significantly low standardized mortality ratios.
CONCLUSION: Some prefectures with high mortality rate from Creutzfeldt-Jakob disease existed in Japan. Some of them had high incidence rate in a survey conducted in 1996 as well.
J Epidemiol 2007; 17: 19-24.

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BACKGROUND: It was reported that 32% of children under five years old in Mongolia had symptoms of rickets. Vitamin D receptor (VDR) gene polymorphism has received attention in relation to bone metabolism. We therefore investigated whether VDR polymorphism is related to high prevalence of rickets in Mongolia and to bone properties in childhood.
METHODS: We conducted a case-control study in Ulaanbaatar involving 80 children aged 7-10 years with a history of rickets (cases) and 72 children with no history of rickets (controls). VDR polymorphism was assessed using BsmI, ApaI, and TaqI, and bone properties were determined by measuring agestandardized midtibial cortical speed of sound (TCSOS).
FINDINGS: Each allelic frequency was verified to satisfy the Hardy-Weinberg equilibrium in cases, controls, and the total sample. The VDR polymorphisms among cases (BB 3%, Bb 18%, bb 80%; AA 15%, Aa 38%, aa 47%; and TT 81%, Tt 17%, tt 3%) did not differ significantly from those among controls (BB 1%, Bb 13%, bb 86%; AA 16%, Aa 46%, aa 38%; and TT 86%, Tt 13%, tt 1%). There were no significant differences in TCSOS according to the VDR genotype among either cases or controls.
CONCLUSIONS: The VDR polymorphism does not play a major role in the development of rickets in Mongolia and has no effect on TCSOS in childhood.
J Epidemiol 2007; 17: 25-29.

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