GSTT1 and GSTM1 deletions, NQO1 C609T polymorphism and risk of chronic myelogenous leukemia in Japanese.

We conducted a prevalent case-control study with 51 chronic myelogenous leukemia (CML) cases and 476 controls to investigate the associations between glutathione S-transferase T1 (GSTT1), glutathione S-transferase M1 (GSTM1) deletions, and the NAD(P)H:quinone oxidoreductase 1 (NQO1) C609T polymorphism with risk of chronic myelocytic leukemia in Japanese. For the GSTT1 deletion, when the GSTT1 positive genotype was defined as the reference, the OR for the GSTT1 deletion genotype was 1.32 (95%CI; 0.74-2.36). For the GSTM1 deletion, when the GSTM1 positive genotype was defined as the reference, the OR for the GSTM1 deletion genotype was 0.95 (95%CI; 0.53-1.69). For NQO1 C609T polymorphism, when the NQO1 609CC genotype was defined as the reference, the ORs for the CT genotype, TT genotype, and CT and TT genotypes combined together were 2.37 (95%CI, 1.21-4.67, P=0.012), 1.44 (0.55-3.74, P=0.012) and 2.12 (1.10-4.08, P=0.025), respectively. The present study revealed that the risk of CML was modulated little by GSTT1 and GSTM1 deletions, but a statistically significant association between NQO1 C609T polymorphism and CML was observed for Japanese. Incidence case-control studies with a larger statistical power are now required to confirm our findings.

Precise definition of anonymization in genetic polymorphism studies.

Anonymization is an essential tool to protect privacy of participants in epidemiological studies. This paper classifies types of anonymization in genetic polymorphism studies, providing precise definitions. They are: 1) unlinkable anonymization at enrollment without a participant list; 2) unlinkable anonymization before genotyping with a participant list; 3) linkable anonymization; 4) unlinkable anonymization for outsiders; and 5) linkable anonymization for outsiders. The classification in view of accessibility to a table including genotype data with directly identifiable data such as names is important; if such tables exist, staff may obtain genotype information about participants. The first three modes are defined here as anonymization unaccessible to genotype data with directly identifiable information for research staff. Anonymization with a key code held by participants is possible with any of the above anonymization modes, by which participants can access to their own genotypes through telephone or internet. A guideline issued on March 29, 2001 with collaboration of three Ministries in Japan defines "anonymization in a linkable fashion" and "anonymization in an unlinkable fashion", "for the purpose of preventing the personal information from being divulged externally in violation of law, the present guidelines or a research protocol", but the contents are not clear in practice. The proposed definitions will be useful when we describe and discuss the preferable mode of anonymization for a given polymorphism study.