Cornelia Baines | PubMed Health

PubMed2004

Case-control study of genotypes in multiple chemical sensitivity: CYP2D6, NAT1, NAT2, PON1, PON2 and MTHFR.

BACKGROUND: Impaired metabolism of toxic chemicals is a postulated mechanism underlying multiple chemical sensitivity (MCS). Because genetic variation alters the rate of chemical metabolism, this study was designed to determine if MCS cases differed from controls for genetic polymorphisms in drug-metabolizing enzymes. METHODS: Female Caucasian participants (203 cases and 162 controls) were drawn from a larger case-control study based on a reproducible and validated case definition. Common polymorphisms for CYP2D6, NAT1, NAT2, PON1, and PON2 were genotyped. RESULTS: Comparing cases and controls, significant differences were found in genotype distributions for CYP2D6 (P = 0.02) and NAT2 (P = 0.03). Compared with the referent homozygous inactive (CYP2D6) or slow (NAT2) metabolizers, the odds for being CYP2D6 homozygous active (OR = 3.36, P = 0.01) and NAT2 rapid (OR = 4.14, P = 0.01) were significantly higher in cases than controls. The odds for being heterozygous for PON1-55 (OR = 2.05, P = 0.04) and PON1-192 (OR = 1.57, P = 0.04) were also significantly higher in cases. CONCLUSIONS: A genetic predisposition for MCS may involve altered biotransformation of environmental chemicals. The CYP2D6 enzyme activates and inactivates toxins; the NAT2 enzyme bioactivates arylamines to protein-binding metabolites. A gene-gene interaction between CYP2D6 and NAT2 suggested that rapid metabolism for both enzymes may confer substantially elevated risk (OR = 18.7, P = 0.002). Our finding parallels others' observation of a link between PON1 heterozygosity and neurological symptoms in Gulf War syndrome. This first demonstration of genetic variation in drug-metabolizing enzymes in association with MCS requires replication. However, it suggests new research directions on genetically variable toxin pathways that might be important in MCS.

Adult↗

PubMed2002

Breast self-examination.

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Breast Neoplasms↗

PubMedDate not supplied

Clinical breast examination: practical recommendations for optimizing performance and reporting.

Clinical breast examination (CBE) seeks to detect breast abnormalities or evaluate patient reports of symptoms to find palpable breast cancers at an earlier stage of progression. Treatment options for earlier-stage cancers are generally more numerous, include less toxic alternatives, and are usually more effective than treatments for later-stage cancers. For average-risk women aged 40 and younger, earlier detection of palpable tumors identified by CBE can lead to earlier therapy. After age 40, when mammography is recommended, CBE is regarded as an adjunct to mammography. Recent debate, however, has questioned the contributions of CBE to the detection of breast cancer in asymptomatic women and particularly to improved survival and reduced mortality rates. Clinicians remain widely divided about the level of evidence supporting CBE and their confidence in the examination. Yet, CBE is practiced extensively in the United States and continues to be recommended by many leading health organizations. It is in this context that this report provides a brief review of evidence for CBE's role in the earlier detection of breast cancer, highlights current practice issues, and presents recommendations that, when implemented, could contribute to greater standardization of the practice and reporting of CBE. These recommendations may also lead to improved evidence of the nature and extent of CBE's contribution to the earlier detection of breast cancer.

Breast Diseases↗