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D T Bishop

Publications and source records attributed to D T Bishop.

At least 91 records · Page 5Linked to original sources
PubMed1995

Genetic linkage studies in non-epidermolytic palmoplantar keratoderma: evidence for heterogeneity.

The palmoplantar keratodermas (PPK) are a group of skin diseases characterized by thickening of the skin of the palms and soles due to abnormal keratinization. We have performed linkage analysis on families affected with three distinct forms of non-epidermolytic PPK (NEPPK): focal, diffuse and punctate. Genetic heterogeneity was demonstrated, with focal NEPPK linked to the region on chromosome 17 harbouring the type I keratin cluster, diffuse NEPPK linked to the region on chromosome 12 containing the type II keratin cluster, and in the punctate NEPPK pedigrees, linkage was excluded to both of these keratin clusters. This study provides evidence for genetic differences between these forms of NEPPK and also between NEPPK and epidermolytic PPK (EPPK) in which mutations in keratin 9 have been demonstrated.

Chromosome Mapping↗
PubMed1995

Candidate regions for a testicular cancer susceptibility gene.

Epidemiological data suggest the presence of a susceptibility gene for testicular cancer in some families. Families with multiple cases of testicular cancer are rare and almost all those reported have only two affected members. We have performed a sib-pair analysis on 35 families in which there are either two or three affected brothers. These families have been typed for 220 autosomal microsatellite markers spaced 10-20 cM throughout the genome. Six regions which gave a LOD score of more than 1.0 on formal linkage analysis or a P value of 0.05 or less using a non-parametric approach are considered as candidate regions for a susceptibility gene. Of particular interest is one region on chromosome 4. Two neighbouring probes in this region both scored positively with LOD score of 2.60 on multipoint analysis. An International Testis Cancer Linkage Consortium has been formed to pool resources and will investigate these findings further with the world-wide collection of families.

Genetic Linkage↗
PubMed1995

Heterogeneity in Li-Fraumeni families: p53 mutation analysis and immunohistochemical staining.

We have screened two families for constitutional TP53 mutations, one family with Li-Fraumeni syndrome and the other with features of this syndrome. We report a germline mutation in exon 7 of the TP53 gene in the family with "Li-Fraumeni-like" syndrome. The mutation occurred at codon 245 and causes a Gly-Ser amino acid change. It was inherited by both affected and unaffected subjects. Malignant tumours from all members of this family showed strong positive nuclear immunohistochemical staining with antibodies CM-1 and DO1, directed against TP53. In contrast, no constitutional TP53 mutations were found in a "classic" Li-Fraumeni family. In this family positive staining was seen in both malignant and normal tissues. These results support previous findings that variants of the Li-Fraumeni syndrome exist since not all LFS families carry TP53 germline mutations. Secondly, immunohistochemical positivity is not synonymous with an underlying mutation and is therefore inadequate as an exclusive diagnostic marker.

Adolescent↗
PubMed1995

Suggested screening guidelines for familial colorectal cancer.

Guidelines for screening for colorectal cancer in subjects with a positive family history of the disease, without the use of DNA based screening, are outlined. These suggestions are derived from (a) the experience of screening 644 subjects at an estimated lifetime risk of dying from colorectal cancer of 10% or more, in the St Mark's Family Cancer Clinic, over six years, and (b) a review of published studies, particularly incorporating the experience of the International Collaboration Group on Hereditary Non-polyposis Colorectal Cancer (HNPCC). Selection of subjects for surveillance depends upon the empirical evaluation of their risk of colorectal cancer, based upon family history details, with the exclusion of a diagnosis of familial adenomatous polyposis in the family. When DNA predictive tests for genes predisposing to HNPCC are available, surveillance can be directed at subjects with a germline mutation known to confer an increased genetic risk of colorectal cancer and discontinued in those at lower (or average) risk. In many subjects, however, DNA testing may still not be possible because of the failure to identify a predisposing mutation in an affected subject in their family. Any surveillance protocol can only be evaluated by long term follow up of those subjects in multiple centres.

Colonoscopy↗
PubMed1995

Prevention of colorectal cancer: guidelines based on new data. WHO Collaborating Center for the Prevention of Colorectal Cancer.

Recently published good quality data are the basis for this update. The newly reported studies include randomized trials, non-randomized cohort studies, and case-control studies; some of the data had mortality reduction as the endpoint. These guidelines, which were developed by the WHO Collaborating Center for the Prevention of Colorectal Cancer at Memorial Sloan-Kettering Cancer Center in conjunction with an International Advisory Committee, include primary prevention, screening of average-risk individuals, screening of individuals with heritable factors for colorectal cancer, surveillance of patients with colorectal polyps, and surveillance of patients with chronic ulcerative colitis. A list of papers reviewed for this update are cited, including recently published trials evaluating faecal occult-blood testing, case-control studies of sigmoidoscopy, the National Polyp study, and familial colon cancer studies. These guidelines will help inform patients and guide physicians in their approach to the prevention of colorectal cancer.

Colorectal Neoplasms↗
PubMed1995

Breast and ovarian cancer incidence in BRCA1-mutation carriers. Breast Cancer Linkage Consortium.

Dominant predisposition to early-onset breast cancer and/or ovarian cancer in many families is known to be the result of germ-line mutations in a gene on chromosome 17q, known as BRCA1. In this paper we use data from families with evidence of linkage to BRCA1 to estimate the age-specific risks of breast and ovarian cancer in BRCA1-mutation carriers and to examine the variation in risk between and within families. Under the assumption of no heterogeneity of risk between families, BRCA1 is estimated to confer a breast cancer risk of 54% by age 60 years (95% confidence interval [CI] 27%-71%) and an ovarian cancer risk of 30% by age 60 years (95% CI 8%-47%). Similar lifetime-risk estimates are obtained by examining the risks of contralateral breast cancer and of ovarian cancer, in breast cancer cases in linked families. However, there is significant evidence of heterogeneity of risk between families; a much better fit to the data is obtained by assuming two BRCA1 alleles, one conferring a breast cancer risk of 62% and an ovarian cancer risk of 11% by age 60 years, the other conferring a breast cancer risk of 39% and an ovarian cancer risk of 42%, with the first allele representing 71% of all mutations (95% CI 55%-87%). There is no evidence of clustering of breast and ovarian cancer cases within families.

Adult↗
PubMed1994

Case-control study of whether subfertility in men is familial.

OBJECTIVE: To test the hypothesis that subfertility in men is familial and to examine the distribution of subfertility within families for consistency with a genetic cause. DESIGN: Case-control study and segregation analysis. SETTING: Two teaching hospitals in Leeds. SUBJECTS: Cases (probands) were men with an abnormal sperm count who attended a subfertility clinic and whose partners had no major factor contravening fertility. Controls were fathers of two or more children recruited through vasectomy clinics or a maternity department. MAIN OUTCOME MEASURES: The incidence of involuntary childlessness among brothers with partners and among sisters and second and third degree male relatives. When possible clinical and laboratory details were obtained from involuntarily childless brothers. RESULTS: Seventeen of the 148 (11.5%) brothers of probands but none of the 169 brothers of controls had sought medical advice for childlessness (P < 0.0005). Four probands had more than one involuntarily childless brother. There were six further brothers whose childlessness was thought to be involuntary bringing the total prevalence of subfertility among brothers of probands to 16%. Segregation analysis was consistent with an autosomal recessive mode of inheritance accounting for 60% of subfertility in men. Seventeen of the 346 (4.9%) uncles of probands and 10 of 420 (2.8%) uncles of controls were reported to be involuntarily childless (P = 0.09), but there was no difference in childlessness among sisters. In three families sperm counts from "affected" brothers confirmed the diagnosis and showed considerable similarities within but not between families. CONCLUSION: Subfertility in men has a familial component, and the observations are consistent with an autosomal recessive mode of inheritance in over half the cases. Several different genes are probably involved.

Adult↗
PubMed1994

Linkage analysis: progress and problems.

Linkage analysis involves identifying the locations of genes responsible for disease by identifying other genes that co-segregate through families with the risk of disease. Subsequently, molecular approaches are applied to find the precise gene involved. Although these approaches have been successful to date, applications to diseases which do not show clear Mendelian inheritance have presented problems. The nature of these problems is discussed.

Alleles↗
PubMed1994

Risks of cancer in BRCA1-mutation carriers. Breast Cancer Linkage Consortium.

Germline mutations in a gene on chromosome 17q known as BRCA1 are responsible for a large proportion of inherited predispositions to breast and ovarian cancer. In 33 families with evidence of linkage to BRCA1, we estimated the risks of breast and ovarian cancer from the occurrence of second cancers in individuals with breast cancer, and examined the risks of other cancers in BRCA1 carriers. 26 contralateral primary breast cancers occurring more than 3 years after a first breast cancer were observed before age 70, giving an estimated cumulative risk of breast cancer in gene carriers of 87% by age 70.23 primary ovarian cancers occurred in women with a previous breast cancer, resulting in an estimated cumulative risk of ovarian cancer of 44% by age 70.87 cancers other than breast or ovarian cancer were observed in individuals with breast or ovarian cancer and their first-degree relatives compared with 69.3 expected, based on national incidence rates. Significant excesses were observed for colon cancer (estimated relative risk [RR] to gene carriers 4.11 [95% CI 2.36-7.15]) and prostate cancer (3.33 [1.78-6.20]). No significant excesses (or deficits) were noted for cancers of other sites. Our study provides estimates of breast and ovarian cancer risks which are useful for counselling BRCA1-mutation carriers. It also shows that carriers are at increased risk of colon and prostate cancer, which may be of clinical significance in certain families if the risks are associated with specific mutations.

Adult↗
PubMed1994

Genetic susceptibility to colorectal cancer in patients under 45 years of age.

A study was conducted to assess the genetic contribution to the development of colorectal cancer in young probands. Of 83 patients aged 45 years or under diagnosed with colorectal cancer in one health region over a 2-year period, 65 or their surviving next of kin were available for interview, from whom were obtained 60 detailed and five limited family histories. Five families fulfilled the Amsterdam criteria and a further eight satisfied less strict criteria for hereditary non-polyposis colorectal cancer, a total of 20 per cent of the cohort. Eleven of these families came from the subgroup of 13 probands who had one or more first-degree relatives with colorectal cancer. Overall the relative risk of colorectal cancer in close relatives was 5.2 (P < 0.0001). This risk was highest for female relatives at 9.7 (P < 0.0001) and relatives of female probands at 6.7 (P < 0.0001). This study highlights the importance of taking a family history in this group of patients. Screening by colonoscopy for all close relatives of young patients with colorectal cancer is recommended.

Adult↗
PubMed1994

Familial risk and genetic susceptibility for breast cancer.

Clinical observations suggest that breast cancer is occasionally inherited as an autosomal dominant disease in families. Epidemiologic studies consistently have shown that a history of breast cancer in a first-degree relative increases a woman's risk of breast cancer when compared with the general population. The risk is similar if a mother or sister is affected and is increased further if both are affected. The difficulty with such an observation is that in itself it does not clarify the nature of the true underlying risk factors which could be genetic or due to the aggregation of environmental risk factors in families. Complex segregation analysis of breast cancer aggregation in families suggests that breast cancer susceptibility is due to an autosomal dominant inheritance of one or more rare genes in a few families in which carriers have a high probability of developing the disease perhaps as great as 100 percent. Close linkage of a breast-cancer-susceptibility gene (BRCA1), between markers of the chromosomal region 17q12-q21 on the long arm of chromosome 17, with breast cancer recently has been reported. Families linked to BRCA1 were more likely to have early onset of breast cancer or have breast and ovarian cancer in the family. It is likely that other genes play a role in the unlinked breast-cancer families. Both the epidemiologic and genetic data suggest that breast cancer is a heterogeneous disease.

Age of Onset↗
PubMed1994

Intron splice acceptor site sequence variation in the hereditary non-polyposis colorectal cancer gene hMSH2.

Common but weakly penetrant mutations of certain genes may confer an increased susceptibility to colorectal cancer and account for a proportion of 'sporadic' cases. We analysed DNA from 111 colorectal cancer cases and 114 controls for a specific candidate sequence variation in the hereditary non-polyposis colorectal cancer gene hMSH2. The variant sequence was found in a quarter of individuals, and there was no difference between cancer cases and controls, according to age of development of cancer or presence of family history. It thus appears that this particular sequence variation is a polymorphism rather than a mutation which increases cancer susceptibility.

Adolescent↗
PubMed1994

Genetic linkage in Muir-Torre syndrome to the same chromosomal region as cancer family syndrome.

The Muir-Torre syndrome, in which sebaceous gland tumours occur in association with internal malignancy, is inherited as an autosomal dominant disorder. Many features of the syndrome are similar to those of the Lynch II cancer family syndrome, and thus the two disorders might share a common genetic basis. We typed two large families with DNA markers on chromosome 2p around D2S123, a site recently shown to be linked to the Lynch II syndrome. LOD scores at this locus demonstrated significant and tight linkage to D2S123, suggesting that defects in the same gene might give rise to both syndromes.

Adult↗
PubMed1994

Genetic heterogeneity in familial malignant melanoma.

Following reports of linkage to chromosome 9p in families with malignant melanoma, we have been studying a series of UK families. Six families were selected with three or more cases of malignant melanoma. We have used a total of twelve markers mapping in the interval 9p13-p23 and constructed a set of haplotypes to study the inheritance of the disease chromosome. Of the six families, three were consistent with linkage to the short arm of 9, although their limited size precluded confirmation of linkage. One family was clearly unlinked, one family was either unlinked, or contains a sporadic case, or delimits the location of the melanoma gene, and one family was essentially uninformative. This is strong evidence for genetic heterogeneity in families with the malignant melanoma phenotype. We have also sequenced exon 2 of the recently identified candidate tumour suppressor gene, p16, in six individuals and found no evidence for germline mutations in this region of the p16 gene in our families with inherited malignant melanoma.

Adolescent↗