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Biomedical subjects

G Suthers

Publications and source records attributed to G Suthers.

16 recordsLinked to original sources
PubMed2002

Sorting nexin 3 (SNX3) is disrupted in a patient with a translocation t(6;13)(q21;q12) and microcephaly, microphthalmia, ectrodactyly, prognathism (MMEP) phenotype.

A patient with microcephaly, microphthalmia, ectrodactyly, and prognathism (MMEP) and mental retardation was previously reported to carry a de novo reciprocal t(6;13)(q21;q12) translocation. In an attempt to identify the presumed causative gene, we mapped the translocation breakpoints using fluorescence in situ hybridisation (FISH). Two overlapping genomic clones crossed the breakpoint on the der(6) chromosome, locating the breakpoint region between D6S1594 and D6S1250. Southern blot analysis allowed us to determine that the sorting nexin 3 gene (SNX3) was disrupted. Using Inverse PCR, we were able to amplify and sequence the der(6) breakpoint region, which exhibited homology to a BAC clone that contained marker D13S250. This clone allowed us to amplify and sequence the der(13) breakpoint region and to determine that no additional rearrangement was present at either breakpoint, nor was another gene disrupted on chromosome 13. Therefore, the translocation was balanced and SNX3 is probably the candidate gene for MMEP in the patient. However, mutation screening by dHPLC and Southern blot analysis of another sporadic case with MMEP failed to detect any point mutations or deletions in the SNX3 coding sequence. Considering the possibility of positional effect, another candidate gene in the vicinity of the der(6) chromosome breakpoint may be responsible for MMEP in the original patient or, just as likely, the MMEP phenotype in the two patients results from genetic heterogeneity.

Abnormalities, Multiple↗
PubMed2001

Long-term outcomes of genetic counseling in women at increased risk of developing hereditary breast cancer.

This multicenter study evaluated the impact of genetic counseling in 218 women at risk of developing hereditary breast cancer. Women were assessed prior to counseling and 12-month post-counseling using self-administered, mailed questionnaires. Compared to baseline, breast cancer genetics knowledge was increased significantly at follow-up, and greater increases in knowledge were associated with educational level. Breast cancer anxiety decreased significantly from baseline to follow-up, and these decreases were associated with improvements in perceived risk. A significant decrease in clinical breast examination was observed at the 12-month follow-up. Findings suggest that women with a family history of breast cancer benefit from attending familial cancer clinics as it leads to increases in breast cancer genetics knowledge and decreases in breast cancer anxiety. The lowered rates of clinical breast examination indicate that the content of genetic counseling may need to be reviewed to ensure that women receive and take away the right message.

Adaptation, Psychological↗
PubMed2001

A single nucleotide polymorphism in the 5' untranslated region of RAD51 and risk of cancer among BRCA1/2 mutation carriers.

RAD51 colocalizes with both BRCA1 and BRCA2, and genetic variants in RAD51 would be candidate BRCA1/2 modifiers. We searched for RAD51 polymorphisms by sequencing 20 individuals. We compared the polymorphism allele frequencies between female BRCA1/2 mutation carriers with and without breast or ovarian cancer and between population-based ovarian cancer cases with BRCA1/2 mutations to cases and controls without mutations. We discovered two single nucleotide polymorphisms (SNPs) at positions 135 g-->c and 172 g-->t of the 5' untranslated region. In an initial group of BRCA1/2 mutation carriers, 14 (21%) of 67 breast cancer cases carried a "c" allele at RAD51:135 g-->c, whereas 8 (7%) of 119 women without breast cancer carried this allele. In a second set of 466 mutation carriers from three centers, the association of RAD51:135 g-->c with breast cancer risk was not confirmed. Analyses restricted to the 216 BRCA2 mutation carriers, however, showed a statistically significant association of the 135 "c" allele with the risk of breast cancer (adjusted odds ratio, 3.2; 95% confidence limit, 1.4-40). BRCA1/2 mutation carriers with ovarian cancer were only about one half as likely to carry the RAD51:135 g-->c SNP. Analysis of the RAD51:135 g-->c SNP in 738 subjects from an Israeli ovarian cancer case-control study was consistent with a lower risk of ovarian cancer among BRCA1/2 mutation carriers with the "c" allele. We have identified a RAD51 5' untranslated region SNP that may be associated with an increased risk of breast cancer and a lower risk of ovarian cancer among BRCA2 mutation carriers. The biochemical basis of this risk modifier is currently unknown.

Adult↗
PubMed2000

Microsatellite instability markers in breast cancer: a review and study showing MSI was not detected at 'BAT 25' and 'BAT 26' microsatellite markers in early-onset breast cancer.

Microsatellite markers may provide evidence of faulty DNA mismatch repair (MMR) via the detection of microsatellite instability (MSI). The choice of microsatellite markers may impact on the MSI detection rate. In hereditary non-polyposis colon cancer (HNPCC), several informative microsatellite markers have been recommended. Two of these, BAT 25 and BAT 26, are quasi-homozygous, enabling analysis of tumour DNA in the absence of paired normal DNA. Sixty-six breast cancer patients under 45 years of age at diagnosis were examined for MSI at BAT 25 and BAT 26. Tumour DNA was extracted from paraffin-embedded tissue. No MSI was detected at the BAT 25 or BAT 26 loci. An additional five microsatellite markers, known to be informative for HNPCC, were examined for MSI in these patients. Apparently-normal profiles were achieved. A tabulated survey of 306 microsatellite markers used to detect MSI in breast cancer revealed that only 35.5% of markers detected MSI at an average rate of 2.9%. The MSI detection rate at the specific HNPCC markers varied from 0% to 10% in breast cancer, with D175250 and TP53 being the HNPCC markers most suitable for analysis of breast cancer. The size of the microsatellite marker's repeat unit did not impact on MSI detection rates. Compiled data from large studies (n > 100) revealed D115988 as the marker with the highest MSI detection rate. Genomic instability pathways of carcinogenesis, characterised by MMR defects and MSI, appear to play a role in the genesis of some breast cancer types.

Adult↗
PubMed2000

Intention to undergo prophylactic bilateral mastectomy in women at increased risk of developing hereditary breast cancer.

PURPOSE: To assess intention to undergo prophylactic bilateral mastectomy and psychologic determinants in unaffected women at increased risk of developing hereditary breast cancer. PATIENTS AND METHODS: Three hundred thirty-three women who were awaiting their initial appointments for risk assessment, advice about surveillance, and prophylactic options at one of 14 familial cancer clinics participated in a cross-sectional, questionnaire-based survey. RESULTS: Nineteen percent of women would consider and 47% would not consider a prophylactic mastectomy, should genetic testing identify a mutation in a breast cancer-predisposing gene, whereas 34% were unsure and 1% had already undergone a prophylactic mastectomy. In a bivariate analysis, women at a moderately increased risk of developing breast cancer had the highest proportion of subjects reporting that they would consider a prophylactic mastectomy (25%), compared with women at high risk (16%) (chi(2) = 7.79; P =.051). In multivariate analyses, consideration of prophylactic mastectomy strongly correlated with high levels of breast cancer anxiety (odds ratio [OR] = 17.4; 95% confidence interval [CI], 4.35 to 69.71; P =. 0001) and overestimation of one's breast cancer risk (OR = 3.01; 95% CI, 1.43 to 6.32; P =.0036), whereas there was no association with objective breast cancer risk (P =.60). CONCLUSION: A significant proportion of women at increased risk of developing hereditary breast cancer would consider prophylactic mastectomy. Although prophylactic mastectomy may be appropriate in women at high risk of developing breast cancer, it is perhaps less so in those who have a moderately increased risk. Such moderate-risk women are likely to benefit from interventions aimed at reducing breast cancer anxiety and correcting exaggerated breast cancer risk perceptions.

Adult↗
PubMed1999

Attitudes toward prophylactic oophorectomy and screening utilization in women at increased risk of developing hereditary breast/ovarian cancer.

OBJECTIVES: The aim of this study was to evaluate ovarian cancer screening uptake and attitudes toward prophylactic oophorectomy in women at risk of developing hereditary breast/ovarian cancer. STUDY METHODS: Ninety-five unaffected women, who approached 1 of 14 familial cancer clinics for advice about their breast/ovarian cancer risk and surveillance and prophylactic options, were assessed in a cross-sectional design when they attended the clinic. RESULTS: Among high-risk women ages 30 and over who had not had a prophylactic oophorectomy, 48% reported ever having had an ovarian ultrasound, and among women ages 50 and over 23% had had a serum CA 125 test. Twenty-three percent of women would consider, and 27% would not consider, a prophylactic oophorectomy should the genetic test indicate a germline mutation associated with hereditary breast/ovarian cancer, while 38% were unsure. Twelve percent had already undergone a prophylactic oophorectomy. Interest in prophylactic oophorectomy was associated with increased breast/ovarian cancer anxiety (chi(2) = 5.14, P = 0.023), but not objective cancer risk (chi(2) = 0.40, P = 0.53). CONCLUSION: Findings demonstrate that breast/ovarian cancer anxiety, rather than objective risk, is the major factor which determines women's attitude to prophylactic oophorectomy. Women are likely to benefit from interventions aimed at reducing breast/ovarian cancer anxiety. Research on the impact of prophylactic oophorectomy would be helpful in the development of educational strategies and decision aids to assist women who are trying to make a decision under conditions of uncertainty.

Adult↗
PubMed1999

Skewed sex ratios in familial holoprosencephaly and in people with isolated single maxillary central incisor.

Autosomal dominant holoprosencephaly is a rare but well documented entity and it can be the result of mutations in the Sonic Hedgehog gene (SHH). The transmitting parent may be normal or have a single maxillary central incisor. We describe a skewed sex ratio among the transmitting parents with SHH mutations, with more mothers than fathers having the mutation (p=0.002). The mechanism underlying this skewed sex ratio is not clear; the SHH mutations do not involve triplet repeats, imprinting is plausible but untested, and there is no evidence that the risk of holoprosencephaly is greater among males carrying such a mutation (p=0.15). We considered the possibility that males with such a mutation are at greater risk of other malformations outside the central nervous system, which could reduce their reproductive fitness. To avoid ascertainment bias in identifying children with various malformations in kindreds with familial holoprosencephaly, we reviewed the reports of people with single maxillary central incisor and no other congenital malformations. Of the 16 cases identified, 13 were female (p=0.0085). We suggest that boys with mutations associated with autosomal dominant holoprosencephaly may be at greater risk of major malformations outside the central nervous system than girls.

Adult↗
PubMed1998

Familial neuronal intranuclear inclusion disease with ubiquitin positive inclusions.

Female monozygotic twins developed upper and lower limb neurogenic weakness in their thirties, followed by cerebellar ataxia, dysarthria and death after an illness duration of about 20 years. Autopsy revealed pathological features typical of neuronal intranuclear inclusion disease (NIID) and positive ubiquitin immunostaining of the inclusions. Two adult sons of one of the twins have now developed an identical illness. This family provides strong evidence of an hereditary form of NIID.

Adult↗
PubMed1998

The impact of molecular diagnosis on familial colorectal cancer.

We have shown the impact of molecular diagnostics related to mutation detection in an extensive family with a strong history of colorectal cancer. The nature and presentation of the cancers suggested that hereditary nonpolyposis colorectal cancer was the most likely cause. The strategies employed have enabled the detection and characterisation of the causative mutation in the proband and predictive testing in the remaining relatives where requested. Using the chemical cleavage of mismatches technique and direct sequencing, the MSH2 and MLH1 genes of the proband were investigated. A single base substitution, C-->T at nucleotide 350, codon 117, of the MLH1 gene was identified. Across the family pedigree at specific points, 22 other relatives have been tested for the mutation by direct DNA sequencing from genomic DNA. Of the total of 23 patients tested to date, 11 have the mutation. In conjunction with appropriate genetic counselling, this service has clarified the genetic status of many individuals within this family. Predictive information provided prior to the development of symptoms enables individuals to make informed choices regarding disease management and the future, removing the anxiety associated with the unknown.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Fronto-facio-nasal dysplasia.

Fronto-facio-nasal dysplasia is a rare cause of facial clefts. The syndrome is characterized by paramedian facial clefts which involve the nose and palpebral fissures resulting in defects of the alae nasi and blepharophimosis, lagophthalmos, and S-shaped palpebral fissures. In addition affected children have ocular malformations such as epibulbar dermoids and colobomata of the iris or optic disk and may have a posterior encephalocele; these features distinguish this condition from fronto-nasal dysplasia and early amnion rupture sequence. We describe a child with unilateral features. Unilateral craniofacial clefts are usually assumed to have a low recurrence risk. However, fronto-facio-nasal dysplasia is an autosomal recessive condition and must be considered in any child with paramedian facial clefts.

Abnormalities, Multiple↗
PubMed1997

Most germ-line mutations in the nevoid basal cell carcinoma syndrome lead to a premature termination of the PATCHED protein, and no genotype-phenotype correlations are evident.

The human homologue of the Drosophila segment polarity gene patched is implicated in the development of nevoid basal cell carcinoma syndrome (NBCCS) and in the genesis of sporadic basal cell carcinomas. In order to examine the phenotypic variability in NBCCS and to highlight functionally important domains of the PTCH protein, we have now screened 71 unrelated NBCCS individuals for mutations in the PTCH exons. We identified 28 mutations that are distributed throughout the entire gene, and most (86%) cause protein truncation. As part of this analysis, we demonstrate that failure of one NBCCS family to show clear linkage to chromosome 9q22.3-31 is most likely due to germinal mosaicism. We have identified three families bearing identical mutations with variable phenotypes, suggesting phenotypic variability in NBCCS is a complex genetic event. No phenotype genotype correlation between the position of truncation mutations and major clinical features was evident. Two missense mutations have been identified, and their location within transmembrane domains supports the notion that PTCH may have a transport function. The preponderance of truncation mutants in the germ line of NBCCS patients suggests that the developmental defects associated with the disorder are most likely due to haploinsufficiency.

Basal Cell Nevus Syndrome↗
PubMed1996

Mutations, malformations and mortality.

Although DNA replication is a very accurate process, a small number of new mutations are generated at every cell division. The generation of a new mutation during the formation of an ovum or sperm cell can cause an early miscarriage or birth defect. The generation of new mutations during embryogenesis can cause a variety of localized birth defects. The molecular delineation of these errors in somatic and gonadal cells has clarified the basis of some birth defects, and has both refined and complicated genetic counselling for a number of paediatric conditions. The processes responsible for these new mutations are present in all cells. For this reason new mutations accumulate in all cells throughout life and contribute to the ageing process. Thus the molecular events that cause many miscarriages and birth defects are the same as those that ultimately lead to death.

Abortion, Spontaneous↗