Referral practices of recent graduate and experienced physiotherapists working in Australian primary care for people with musculoskeletal conditions.

BACKGROUND: People with musculoskeletal conditions often seek care from physiotherapists. Some, particularly those at risk of poor outcomes, may benefit from referral to physiotherapists with expertise in managing musculoskeletal conditions and/or multidisciplinary care. Understanding referral practices of physiotherapists, and how experience influences those practices, may assist in implementing optimal care pathways in primary care. AIMS: Explore (i) current referral practices of recent graduate and experienced physiotherapists who manage musculoskeletal conditions; (ii) opinions about referral to specialist physiotherapists for people at risk of poor outcomes. METHODS: This qualitative study consisted of 23 semi-structured interviews with recent graduate (n = 9) and experienced physiotherapists (n = 14) working in primary care. Perspectives of participants' current referral practices (to whom, when and why they are referred) and referral to specialist physiotherapists were sought. Interviews were recorded and transcribed verbatim prior to analysis. RESULTS: Referral practices for both groups were influenced by specific diagnoses, complexity of presentations, confidence, self-awareness, the clinical environment and system-related factors. Experienced physiotherapists were more confident and specific in their referrals and had established trusted networks compared with new graduates. Early referral to specialist physiotherapists was more likely when therapists were co-located. Barriers to early referral were lack of awareness, health system factors and impact on the patient (e.g., financial, time, continuity of care). CONCLUSION: Understanding factors influencing referral decisions may improve both intra- and interprofessional care for people with musculoskeletal conditions. Referral of people at risk of poor outcomes to specialist physiotherapists may be improved by greater intraprofessional awareness and clarity of roles.

Prostate cancer age-standardised incidence increase between 2006 and 2016 in Gauteng Province, South Africa: A laboratory data-based analysis.

BACKGROUND: Prostate cancer (PCa) is the leading male neoplasm in South Africa (SA) and is the second most frequently diagnosed cancer among men globally. Age-specific incidence rates (ASIRs) vary by up to 189-fold globally, with an ASIR of 68.0 per 100 000 in 2018 in SA. OBJECTIVES: To describe PCa among men undergoing prostate biopsy in Gauteng Province, SA. METHODS: We undertook a retrospective descriptive study using prostate biopsy data collected from the National Health Laboratory Service (NHLS) database between 2006 and 2016. We extracted the Systematized Nomenclature of Medicine (SNOMED) clinical terms morphology and topography codes to assign histological findings using the International Classification of Diseases for Oncology. PCa was defined as adenocarcinoma with a reported Gleason Score (GS). The new grade group (GG) based on the GS is defined as follows; (i) GG1 for a GS ≤6; (ii) GG2 for a GS of 3 + 4 = 7 ; (iii) GG3 for a GS of 4 + 3 = 7; (iv) GG4 for a GS of 8; and (v) GG5 for a GS ≥9. Higher-grade disease was defined as GG4 and GG5 (GS ≥8), in line with local guidelines. We reported associations of PCa with a GS ≥7 with age and race and used provincial and world standard population data to determine annual ASIRs. RESULTS: We identified 22 937 biopsies referred to the NHLS between 2006 and 2016. Of the 6 448 biopsies (39%) with a PCa finding for black Africans, 46% were diagnosed with high-risk PCa compared with 36 - 40% for other race groups (p<0.0001). Black Africans were more likely than whites to have GG4 or GG5 PCa (odds ratio 1.45; 95% confidence interval 1.27 - 1.67). The ASIR increased from 44.9 per 100 000 in 2006 to 57.3 per 100 000 in 2016. CONCLUSIONS: Black African men were significantly more likely to present with PCa with a GS ≥8 (GG4 and GG5) compared with the other racial groups in Gauteng. The ASIR increased dramatically during the study period, perhaps as a result of increased screening and awareness. There is a need for additional research to better understand why black African men present with higher-grade disease.

Genetic variation in IL-16 miRNA target site and time to prostate cancer diagnosis in African-American men.

BACKGROUND: Men with a family history of prostate cancer and African-American men are at high risk for prostate cancer and in need of personalized risk estimates to inform screening decisions. This study evaluated genetic variants in genes encoding microRNA (miRNA) binding sites for informing of time to prostate cancer diagnosis among ethnically diverse, high-risk men undergoing prostate cancer screening. METHODS: The Prostate Cancer Risk Assessment Program (PRAP) is a longitudinal screening program for high-risk men. The eligibility includes men aged between 35 and 69 years with a family history of prostate cancer or African descent. Participants with 1 follow-up visit were included in the analyses (n=477). Genetic variants in genes encoding miRNA binding sites (ALOX15 (arachidonate 15-lipooxygenase), IL-16, IL-18 and RAF1 (v-raf-1 murine leukemia viral oncogene homolog 1)) previously implicated in prostate cancer development were evaluated. Genotyping methods included Taqman SNP Genotyping Assay or pyrosequencing. Cox models were used to assess time to prostate cancer diagnosis by risk genotype. RESULTS: Among 256 African Americans with one follow-up visit, the TT genotype at rs1131445 in IL-16 was significantly associated with earlier time to prostate cancer diagnosis vs the CC/CT genotypes (P=0.013), with a suggestive association after correction for false discovery (P=0.065). Hazard ratio after controlling for age and PSA for TT vs CC/CT among African Americans was 3.0 (95% confidence interval: 1.26-7.12). No association with time to diagnosis was detected among Caucasians by IL-16 genotype. No association with time to prostate cancer diagnosis was found for the other miRNA target genotypes. CONCLUSIONS: Genetic variation in IL-16 encoding miRNA target site may be informative of time to prostate cancer diagnosis among African-American men enrolled in prostate cancer risk assessment, which may inform individualized prostate cancer screening strategies in the future.

Non-cancer endpoints in BRCA1/2 carriers after risk-reducing salpingo-oophorectomy.

Risk-reducing salpingo-oophorectomy (RRSO) significantly reduces the risk of ovarian cancer and breast cancer in pre-menopausal women with BRCA1 and BRCA2 (B1/2) mutations. Despite its clear benefits, little is known about non-cancer endpoints in this population. Medical records were examined in 226 B1/2 mutation carriers, who had previously undergone RRSO with a focus on bone health as well as the frequency of hypertension, hyperlipidemia, coronary artery disease (CAD), myocardial infarction (MI), diabetes, hypothyroidism and depression. From the medical records, DEXA scans, medications and medical conditions were recorded. Of the 226 patient records examined, 16% (36/226) had hypertension, 17% (39/226) hyperlipidemia, 2% (5/226) CAD or MI, 2% (4/226) diabetes, 13% (29/226) hypothyroidism and 14% (31/226) depression. DEXA results were available in 152 women. Of those DEXA scans, 71% (108/152) were abnormal (57% osteopenia and 14% osteoporosis). Among women who underwent RRSO prior to age 50, 71% (62/88) had osteopenia/osteoporosis. Although there was no difference in osteopenia/osteoporosis in women with RRSO prior to age 50 compared to those RRSO > 50, the age at follow up in these two groups differs greatly (mean age 44.7 vs. 60.6), suggesting that both current age and age at RRSO contribute to bone health assessment. In summary, here, we report the prevalence of non-cancer endpoints in a cohort of B1/2 mutation carriers and note a particularly high rate of osteopenia and osteoporosis in B1/2 with breast cancer undergoing RRSO prior to 50. Despite the risk reduction RRSO offers, attention should be paid to non-cancer endpoints, particularly bone health, in this population.

Association of obesity with tumor characteristics and treatment failure of prostate cancer in African-American and European American men.

PURPOSE: The impact of body mass index on tumor characteristics and treatment failure in prostate cancer is not well understood in diverse ethnic groups. We evaluated the effect of body mass index in African-American and European American patients from a radical prostatectomy cohort between 1995 and 2004 with regard to tumor histopathological characteristics and biochemical relapse-free survival. MATERIALS AND METHODS: A total of 924 patients were studied to evaluate whether obese men (body mass index greater than 30) had different preoperative and postoperative tumor characteristics or biochemical relapse-free survival compared to nonobese men. There were 784 European American and 140 African-American patients analyzed using failure time models, adjusted for age, preoperative prostate specific antigen, tumor stage and race. RESULTS: Mean and median followup was 42 and 36 months, respectively. African-American men were significantly more obese than European American men. Mean body mass index was 29.0 in African-American and 28.1 in European American men (p = 0.003). African-American men (OR 2.30, 95% CI 1.04-5.1) were more likely to have higher tumor stage on final pathology. Obesity was a risk factor for biochemical failure in African-American men (adjusted hazard ratio 5.49, 95% CI 2.16-13.9) but not in European American men (HR 1.41, 95% CI 0.96-2.08), and this difference was statistically significant (p value for interaction 0.036). CONCLUSIONS: Obesity is associated with poorer tumor prognostic characteristics and decreased biochemical relapse-free survival, particularly in African-American men. These data suggest that obesity may in part explain the poorer prostate cancer prognosis seen in African-American men compared to other racial and ethnic groups.

Pharmacogenetic modulation of combined hormone replacement therapy by progesterone-metabolism genotypes in postmenopausal breast cancer risk.

Combined hormone replacement therapy (CHRT) containing estrogens and progestins is associated with breast cancer risk. The authors evaluated interactions between CHRT use and progestin metabolism genotypes at CYP3A4 and the progesterone receptor (PGR) and their effects on breast cancer risk using the population-based Women's Insights and Shared Experiences (WISE) Study (1999-2002) of postmenopausal Caucasian women (522 breast cancer cases, 708 controls). The authors observed an elevated risk of ductal tumors in women with 3 or more years of CHRT use and PGR 331A alleles compared with those who had neither factor (odds ratio = 3.35, 95% confidence interval (CI): 1.13, 9.99; two-sided p(interaction) = 0.035). They also observed an elevated risk of progesterone receptor-positive tumors in women who had had 3 or more years of CHRT use and PGR 331A alleles compared with those who had neither factor (odds ratio = 3.82, 95% CI: 1.26, 11.55; p = 0.028). Finally, they observed an increased risk of estrogen receptor-negative tumors in women without CHRT exposure and CYP3A4*1B alleles compared with those who had neither factor (odds ratio = 6.46, 95% CI: 2.02, 20.66; p = 0.024), although the biologic interpretation of this result requires further study. When stratified by recency of use, PGR effects were observed only in current CHRT users, while CYP3A4 effects were observed only in former CHRT users. Breast cancer risk in women who have used CHRT may be influenced by genetic factors involved in progestin metabolism.

Association of prostate cancer family history with histopathological and clinical characteristics of prostate tumors.

Genetic factors may be used not only to assess risk of prostate cancer development but also to evaluate prostate cancer outcomes including clinical prognosis, treatment methods, and treatment response. To assess the role of family history on prostate cancer outcomes, we evaluated tumor characteristics, diagnostic precursors and biochemical (prostate specific antigen) relapse-free survival in men with and without a family history of prostate cancer. A total of 684 prostate cancer cases unselected for family history were identified from an ongoing hospital based prostate cancer case-control study between 1995 and 2002. Self-reported family history was grouped within the following categories: none, any, moderate (one affected first or second degree relative) and high (2 or more affected first or second degree relatives). We further considered groups defined by early (before age 60) and late (after age 60) age at diagnosis. Overall, tumor stage was not significantly associated with any (odds ratio [OR] = 1.43 95% confidence interval [CI] = 1.00-2.05) or moderate (OR = 1.48, 95% CI = 1.0-2.19) family histories. Men diagnosed before age 60, however, had higher tumor stages if they had any (OR = 2.19, 95% CI = 1.28-3.75) or moderate (OR = 2.15, 95% CI = 1.2-3.9) family histories. Men diagnosed after age 60 with any family history were significantly more likely to experience biochemical (PSA) failure (Hazard ratio [HR] = 2.60, 95%CI = 1.08-6.25). Men with any and moderate family histories were at significantly increased risk of biochemical failure (HR = 2.49, 95%CI = 1.25-4.95 and HR = 2.46, 95% CI = 1.17-5.16, respectively). Moderate family history increased probability of seminal vesicle invasion (OR = 2.14, 95%CI = 1.06-4.34). Our results suggest that a family history of prostate cancer may be associated with predictors of clinical outcome in prostate cancer cases unselected for a family history of prostate cancer.

Increased transcriptional activity of the CYP3A4*1B promoter variant.

Numerous single nucleotide polymorphisms (SNPs) have been identified in the human genome, yet the functional significance of most is unknown. CYP3A4 is a key enzyme in the metabolism of numerous compounds. An A-->G substitution 290 bp upstream of the CYP3A4 transcription start site (CYP3A4*1B) has been associated with cancer phenotypes, but its phenotypic effects are unclear. To investigate the functional significance of CYP3A4*1B, we generated two luciferase reporter constructs: 1-kb (denoted L, long) and 0.5-kb (denoted S, short) promoter fragments containing either the variant (V(L),V(S)) or the wild-type (W(L), W(S)) sequences. We evaluated the effect of the variant sequence in the HepG2 and MCF-7 cell lines, and in primary human hepatocytes from three donors. Reporter constructs with the variant sequence had 1.2- to 1.9-fold higher luciferase activity than constructs with wild-type sequence in the cell lines (P < 0.0001) and hepatocytes (P = 0.021, P = 0.027, P = 0.061). The ratio of transcriptional activity for V(S):W(S) was similar to the V(L):W(L) ratio in HepG2 cells, but the V(S):W(S) ratio was consistently less than the V(L):W(L) ratio in MCF-7 cells. This suggests that CYP3A4 expression is higher from the variant promoter and that a repressor sequence may exist in the longer constructs. Electrophoretic mobility shift assays demonstrated specific binding of a component of HepG2 nuclear extract to both wild-type and variant promoters with consistently higher binding affinities to the wild-type sequence. This suggests the existence of a transcriptional repressor responsible for the lower CYP3A4*1A activity. Therefore, the phenotypic effects of the variant CYP3A4*1B may be associated with enhanced CYP3A4 expression due to reduced binding of a transcriptional repressor.

Population frequencies of single nucleotide polymorphisms (SNPs) in immuno-modulatory genes.

Inherited polymorphisms in immuno-modulatory genes may contribute to variations in immune function and genetic susceptibility for complex diseases, including cancer. We report results from a comprehensive study to discover novel single nucleotide polymorphisms (SNPs) and to estimate allelic frequency for both novel and known coding and regulatory region SNPs in genes encoding proteins that have been implicated in the immune response to tumors. We identified 12 novel nucleotide substitution variants and one deletion variant in 17 genes analyzed (TGFBETA;R, BETA;2M, IFNGAMMA;, TNFALPHA;, TNFALPHA;R, LTALPHA;, IL-6, IL-12, IL-2, IL-1ALPHA;, IL-1BETA;, IL-1RN, IL-10, CTLA4, CD40L, FAS and FASL). We determined the frequency of these novel polymorphisms, as well as 17 previously identified polymorphisms, in a control sample of 158 individuals, approximately half of which were Caucasian (n = 74) and half of which were African American (n = 84). Significant differences in allele frequencies were observed between the two racial groups for 13/17 genes tested. These allelic variations maybe associated with alterations in immune function and thus susceptibility to a number of complex disease states such as cancer.

Clinical characteristics of prostate cancer in African Americans, American whites, and Senegalese men.

OBJECTIVES: To describe the clinical features of prostate cancer in Senegalese men and compare these features with those found in African-American and white American men. METHODS: We identified an unselected series of 121 patients with prostate cancer diagnosed at two hospitals in Dakar, Senegal between 1997 and 2002. Medical record abstractions were undertaken to evaluate the prostate tumor characteristics, patient age at diagnosis, prostate-specific antigen (PSA) levels, and reason for referral. In addition, these characteristics were compared with a sample of 455 U.S. white men and 60 African-American men with prostate cancer who were studied as part of a prostate cancer case-control study. RESULTS: Senegalese men had a significantly worse tumor stage than Americans (41.3% versus 18.8%, P <0.001), a significantly worse mean PSA level at diagnosis (mean PSA 72.7 ng/mL versus 9.0 ng/mL in Americans; P <0.001), and were diagnosed at a significantly later age than U.S. men (69 years versus 61 years, P <0.001). U.S. men were most likely to be diagnosed with prostate cancer after an elevated PSA test, and Senegalese men were most often diagnosed after presenting for prostate-related symptoms. CONCLUSIONS: These observations are not unexpected given the differences in the patterns of prostate cancer screening and health care in the United States compared with Senegal. However, our data provide descriptive information about the characteristics of prostate cancer diagnosed in Senegal and highlight differences in the characteristics and detection of these tumors across populations with very different healthcare systems.

Group sequential methods and sample size savings in biomarker-disease association studies.

Molecular epidemiological association studies use valuable biosamples and incur costs. Statistical methods for early genotyping termination may conserve biosamples and costs. Group sequential methods (GSM) allow early termination of studies on the basis of interim comparisons. Simulation studies evaluated the application of GSM using data from a case-control study of GST genotypes and prostate cancer. Group sequential boundaries (GSB) were defined in the EAST-2000 software and were evaluated for study termination when early evidence suggested that the null hypothesis of no association between genotype and disease was unlikely to be rejected. Early termination of GSTM1 genotyping, which demonstrated no association with prostate cancer, occurred in >90% of the simulated studies. On average, 36.4% of biosamples were saved from unnecessary genotyping. In contrast, for GSTT1, which demonstrated a positive association, inappropriate termination occurred in only 6.6%. GSM may provide significant cost and sample savings in molecular epidemiology studies.

Ethnic differences in the frequency of prostate cancer susceptibility alleles at SRD5A2 and CYP3A4.

OBJECTIVES: Ethnic differences in prostate cancer incidence are well documented, with African-Americans having among the highest rates in the world. Ethnic differences in genotypes for genes associated with androgen metabolism including SRD5A2 and CYP3A4 also may exist. The aim of this study was to evaluate differences in these genotypes by ethnicity. METHODS: We studied cancer-free controls representative of four groups: 147 African Americans, 410 Caucasian-Americans, 129 Ghanaians, and 178 Senegalese. PCR-based genotype analysis was undertaken to identify two alleles (V89L, A49T) at SRD5A2 and *1B allele at CYP3A4. RESULTS: Differences were observed for V89L (variant frequency of 30% in Caucasians, 27% in African Americans, 19% in Ghanaians, and 18% in Senegalese, p = 0.002) and were observed for CYP3A4*1B (variant frequencies of 8% in Caucasians, 59% in African Americans, 81% in Ghanaians, and 78% in Senegalese, p = 0.0001). Pooled data combining the present data and previously published data from from Asian, Hispanic, and Arab cancer-free controls showed significant ethnic differences for SRD5A2 and CYP3A4 polymorphisms. Overall, Asians were least likely to have alleles associated with increased prostate cancer risk, while Africans were most likely to have those alleles. CONCLUSIONS: These results suggest that ethnicity-specific differences in genotype frequencies exist for SRD5A2 and CYP3A4. Africans and African-Americans have the highest frequency of those alleles that have previously been associated with increased prostate cancer risk. Future studies should address whether allele frequency differences in part explain differences in prostate cancer incidence in these populations.

Modification of BRCA1- and BRCA2-associated breast cancer risk by AIB1 genotype and reproductive history.

Women who have inherited a germ-line mutation in the BRCA1 or BRCA2 (BRCA1/2) genes have a greatly increased risk of developing breast cancer compared with the general population. However, there is also substantial interindividual variability in the occurrence of breast cancer among BRCA1/2 mutation carriers. We hypothesize that genes involved in endocrine signaling may modify the BRCA1/2-associated age-specific breast cancer penetrance. We studied the effect of alleles at the AIB1 gene using a matched case-control sample of 448 women with germ-line BRCA1/2 mutations. We found that these women were at significantly higher breast cancer risk if they carried alleles with at least 28 or 29 polyglutamine repeats at AIB1, compared with women who carried alleles with fewer polyglutamine repeats [odds ratio (OR), 1.59; 95% confidence interval (CI), 1.03-2.47 and OR, 2.85; 95% CI, 1.64-4.96, respectively]. Late age at first live birth and nulliparity have been associated with increased breast cancer risk. We observed increases in BRCA1/2-associated breast cancer risk in women who were either nulliparous or had their first live birth after age 30 (OR, 3.06; 95% CI, 1.52-6.16). Women were at significantly increased risk if they were nulliparous or had a late age at first live birth and had AIB1 alleles no shorter than 28 or 29 or more AIB1 polyglutamine repeats (OR, 4.62; 95% CI, 2.02-10.56 and OR, 6.97; 95% CI, 1.71-28.43, respectively) than women with none of these risk factors. Our results support the hypothesis that pathways involving endocrine signaling, as measured through AIB1 genotype and reproductive history, may have a substantial effect on BRCA1/2-associated breast cancer risk.

Nucleotide substitution in the ectodomain of trail receptor DR4 is associated with lung cancer and head and neck cancer.

Allelic loss of chromosome 8p21-22 occurs frequently in cancer, including lung and head and neck squamous cell cancer. The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors, including proapoptotic DR4 and KILLER/DR5, are located on 8p21-22. TRAIL receptors are candidate tumor suppressor genes, because their inactivation would be expected to result in deficient apoptotic signaling. To investigate the involvement of DR4 in human cancer, we have determined the genomic structure of DR4 and screened 31 lung cancer cell lines [14 small cell lung cancer and 17 non-small cell lung cancer (NSCLC)], many with deletions at 8p21-22, and 21 primary NSCLC samples for mutations in DR4. We found two missense alterations in the ectodomain of DR4. One, at nucleotide 626, changes a cytosine to a guanine (C626G) and results in a substitution of an arginine for threonine. The other, at nucleotide 422, changes a guanine to adenine (G422A) and results in a substitution of a histidine for arginine. Using genomic DNA sequencing and RFLP analysis, we show that these two alterations cosegregated in 96% of all of the samples (n = 243) evaluated (tumor and normal). The frequency of being homozygous for both altered alleles was 35% in the lung cancer cell lines but only 13% in age- and race-matched controls, which was a significant increase (chi(2) = 5.2, P = 0.023). The frequency of homozygosity for both alleles was also significantly increased in the primary NSCLC samples (chi(2) = 9.2, P = 0.002) as compared with the age- and race-matched controls. To determine whether the altered alleles are specific for lung cancer, we evaluated 19 head and neck squamous cell cancer and 25 gastric adenocarcinoma samples. Forty-seven % of the former and 44% of the latter were homozygous for both the C626G and G422A alterations, and this was significantly elevated relative to age- and race-matched controls (chi(2) = 8.6, P = 0.003 and chi(2) = 8.2, P = 0.004). These alterations result in amino acid changes in or near the ligand-binding domain of DR4 and, based on the crystal structure of DR5 and its homology with DR4, have the potential to affect TRAIL binding to DR4. Our results suggest that the altered DR4 alleles may be associated with, and should be investigated additionally as potential markers for, predisposition to common malignancies.

Interaction of glutathione S-transferase M1 and T1 genotypes and malignant melanoma.

The mu and theta classes of glutathione S-transferases (GST) may affect the development of cutaneous malignant melanoma (CMM) by decreasing cellular oxidative stress in skin. These isozymes are absent in a large proportion of the population because of germ-line homozygous deletions in the genes encoding GSTM1 and GSTT1. To determine the association between GSTM1 and GSTT1 homozygous deletions (GSTM1 null and GSTT1 null, respectively) and CMM, we studied 212 patients with CMM, 150 patients with CMM and dysplastic nevi (DN), 147 patients with DN alone, and 124 healthy persons without CMM or DN. Comparing CMM cases (n = 362) to participants without CMM (n = 271), we found no association with GSTM1 null [odds ratio (OR), 1.2; 95% confidence interval (CI), 0.86-1.6] or GSTT1 null (OR, 0.82; 95% CI, 0.56-1.2), either independently or in combination (OR, 1.4; 95% CI, 0.81-2.2), after adjusting for age. However, among the subset of participants with red or blond hair, those with CMM were twice as likely to carry GSTM1 null (OR, 2.2; 95% CI, 1.2-4.2) and nearly 10-fold more likely to carry both GSTM1 null and GSTT1 null (OR, 9.5; 95% CI, 1.2-73) compared with those without CMM. These data suggest that among persons with hair colors traditionally associated with increased risk for melanoma, absence of both GSTM1 and GSTT1 may act to further elevate CMM risk.

Sulfation pharmacogenetics: SULT1A1 and SULT1A2 allele frequencies in Caucasian, Chinese and African-American subjects.

Sulfotransferase (SULT) enzymes catalyze the sulfate conjugation of drugs, other xenobiotics, neurotransmitters and hormones. The genes for SULT1A1 and SULT1A2 contain common genetic polymorphisms that are associated with individual variations in levels of enzyme activity as well as variations in biochemical and physical properties. We set out to compare the frequencies of common SULT1A1 and SULT1A2 alleles in Caucasian, Chinese and African-American subjects. Allele frequencies for SULT1A1*1, *2 and *3 in 242 Caucasian subjects were 0.656, 0.332 and 0.012, respectively. Frequencies of those same alleles were significantly different in 290 Chinese subjects: 0.914, 0.080 and 0.006, respectively, as were frequencies in 70 African-American subjects: 0.477, 0.294 and 0.229, respectively. Ethnic variation in allele frequencies was also observed for SULT1A2, with frequencies in Caucasian subjects for SULT1A2*1, *2 and *3 of 0.507, 0.389 and 0.104; frequencies in Chinese of 0.924 and 0.076 with no *3 alleles observed; and, finally, in African-Americans frequencies of 0.637, 0.249 and 0.114, respectively. We also found that SULT1A1*2 and SULT1A2*2, the most common variant alleles for these two genes, were in positive linkage disequilibrium in all three populations studied, with D' values of 0.776 in Caucasian (P < 0.001), 0.915 in Chinese (P < 0.001) and 0.864 in African-American subjects (P < 0.001). These observations represent a step towards determining the possible functional implications for individual variations in sulfate conjugation of common genetic polymorphisms for SULT1A1 and SULT1A2.