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E J Sawyer

Publications and source records attributed to E J Sawyer.

7 recordsLinked to original sources
PubMed2003

An ancestral Ashkenazi haplotype at the HMPS/CRAC1 locus on 15q13-q14 is associated with hereditary mixed polyposis syndrome.

The putative locus for hereditary mixed polyposis syndrome (HMPS) in a large family of Ashkenazi descent (SM96) was previously reported to map to chromosome sub-bands 6q16-q21. However, new clinical data, together with molecular data from additional family members, have shown 6q linkage to be incorrect. A high-density genomewide screen for the HMPS gene was therefore performed on SM96, using stringent criteria for assignment of affection status to minimize phenocopy rates. Significant evidence of linkage was found only on a region on chromosome 15q13-q14. Since this region encompassed CRAC1, a locus involved in inherited susceptibility to colorectal adenomas and carcinomas in another Ashkenazi family (SM1311), we determined whether HMPS and CRAC1 might be the same. We found that affected individuals from both families shared a haplotype between D15S1031 and D15S118; the haplotype was rare in the general Ashkenazi population. A third informative family, SM2952, showed linkage of disease to HMPS/CRAC1 and shared the putative ancestral haplotype, as did a further two families, SMU and RF. Although there are probably multiple causes of the multiple colorectal adenoma and cancer phenotype in Ashkenazim, an important one is the HMPS/CRAC1 locus on 15q13-q14.

Adenomatous Polyposis Coli↗
PubMed2002

Molecular characteristics of serrated adenomas of the colorectum.

BACKGROUND: Serrated adenomas (SAs) of the colorectum combine architectural features of hyperplastic polyps and cytological features of classical adenomas. Molecular studies comparing SAs and classical adenomas suggest that each may be a distinct entity; in particular, it has been proposed that microsatellite instability (MSI) distinguishes SAs from classical adenomas and that SAs and the colorectal cancers arising from them develop along a pathway driven by low level microsatellite instability (MSI-L). AIMS: To define the molecular characteristics of SAs of the colorectum. MATERIALS AND METHODS: We analysed 39 SAs from 27 patients, including eight SAs from patients with familial adenomatous polyposis (FAP). We screened these polyps for selected molecular changes, including loss of heterozygosity (LOH) close to APC (5q21) and CRAC1 (15q13-q22), MSI, and mutations of K-ras, APC, p53, and beta-catenin. Expression patterns of beta-catenin, p53, MLH1, MSH2, E-cadherin, and O(6)-methylguanine DNA methyltransferase (MGMT) were assessed by immunohistochemistry. Comparative genomic hybridisation was performed on several polyps. RESULTS: MSI was rare (<5% cases) and there was no loss of expression of mismatch repair proteins. Wnt pathway abnormalities (APC mutation/LOH, beta-catenin mutation/nuclear expression) occurred in 11 SAs, including 6/31 (19%) non-FAP tumours. CRAC1 LOH occurred in 23% of tumours. K-ras mutations and p53 mutations/overexpression were found in 15% and 8% of SAs, respectively. Loss of MGMT expression occurred in 18% of polyps and showed a borderline association with K-ras mutations. Aberrant E-cadherin expression was found in seven polyps. Comparative genomic hybridisation detected no gains or deletions of chromosomal material. CONCLUSIONS: The serrated pathway of colorectal tumorigenesis appears to be heterogeneous. In common with classical adenomas, some SAs develop along pathways involving changes in APC/beta-catenin. SAs rarely show MSI or any evidence of chromosomal-scale genetic instability. K-ras mutations may however be less common in SAs than in classical adenomas. Some SAs may harbour changes in the CRAC1 gene. Changes in known genes do not account for the growth of the majority of SAs.

Adenoma↗
PubMed2000

Molecular analysis of phyllodes tumors reveals distinct changes in the epithelial and stromal components.

Phyllodes tumors are fibroepithelial mammary lesions that tend to behave in a benign fashion but may undergo sarcomatous transformation. A study of clonality in these tumors has suggested that the epithelial component is polyclonal, but the stroma is monoclonal, and thus forms the neoplastic component of the lesion. In this study microsatellites on chromosome 1q and chromosome 3p were assessed for allelic imbalance (AI) in 47 phyllodes tumors; in all cases stroma and epithelium were analyzed separately. Ten of 42 (24%) phyllodes tumors showed AI at one or more markers on 3p, and 14 of 46 (30%) showed AI on chromosome 1. Five tumors had changes in both the epithelium and stroma. Eight tumors had changes only detectable in the stroma and eight, changes in the epithelium only. Three tumors exhibited low-level microsatellite instability in the epithelium but not in the stroma. The results show that AI on 3p and 1q does occur in phyllodes tumors and that it can occur in both the stroma and epithelium, sometimes as independent genetic events. These unexpected findings throw into doubt the classical view that phyllodes tumors are simply stromal neoplasms and raise questions about the nature of stromal and epithelial interactions in these tumors.

Alleles↗
PubMed1999

A lesson in the management of testicular cancer in a patient with a solitary testis.

Five per cent of patients with germ cell tumours of the testis will develop a further tumour in the contralateral testis. Standard treatment in such cases is a second orchidectomy, resulting in infertility, hormone replacement, and psychological morbidity. In this case report we explore the role of testis conservation in these patients and also show that there is a risk of removing a potentially normal testis if a histological diagnosis is not sought prior to orchidectomy.

Adult↗
PubMed1997

Low dose palliative radiotherapy in low grade non-Hodgkin's lymphoma.

The clinical picture of disseminated (stage 3 and 4) low grade non-Hodgkin's lymphoma (NHL) is one of continuing relapse. Management options include observation only in asymptomatic patients, single agent chlorambucil or localised radiotherapy in patients with symptomatic nodal disease. Radiation doses of 25-40 Gray in 10-20 fractions have been the standard approach in low grade NHL, but in 1994 Ganem et al. [Hematol. Oncol. 8: 225-233, 1994] reported the use of low dose radiotherapy (LDRT)--4 Gray in 2 fractions over 3 days--for the palliation of symptomatic disease in patients with disseminated, chemoresistant low grade NHL. We describe here our early experience with this schedule.

Aged↗