Biomedical subjects
Publications and source records attributed to H Sobol.
We have examined 30 families with multiple endocrine neoplasia type 2a (MEN2A). Linkage studies indicate that the gene for MEN2A is located on chromosome 10, tightly linked to the D10Z1 locus.
Human mannose-binding lectin (MBL) is a serum protein which appears to function as an opsonin in first line host defense. In situ hybridization studies assign the human MBL gene to chromosome 10q11.2----q21. A restriction fragment length polymorphism (RFLP) was found using TaqI with a 0.8-kb cDNA probe for MBL (probe 48-11), yielding heterozysity in 34% of individuals tested. Using this biallelic RFLP, linkage analysis of 30 families confirms the assignment of MBL to the region of multiple endocrine neoplasia, type 2a (MEN2A) with a maximum lod score of 7.54 at a recombination fraction of 0.00 (males) and 0.097 (females). The presence of two crossovers between MEN2A and MBL in these families indicates that a defect of MBL itself is not the cause of the hereditary thyroid cancer syndrome. The addition of MBL to the genetic map of the pericentromeric region of chromosome 10 should prove useful for improved localization of the MEN2A mutation.
Two forms of neurofibromatosis are currently described. Von Reckinghausen Neurofibromatosis (NF 1) is the classic and common form, recently localised to chromosome 17. Neurofibromatosis type 2 (NF 2) or bilateral acoustic Neurofibromatosis, formerly the "central form" of von Reckinghausen disease, is characterized by multiple brain tumors, most often bilateral acoustic neuromas. The NF 2 mutation lies on the long arm of chromosome 22. The two forms predispose to benign or malignant familial tumors, derived from neural crest germ lines, such as Schwann cells. Rapid progress in the understanding of mechanisms underlying neurological tumor formation is expected in these inherited diseases. Molecular biology will allow the precise identification of genes responsible for the neurofibromatose syndromes. Practical applications, such as screening of individuals at risk for the disease will soon be available. Medical follow-up and genetic counselling should improve as a result of these advances.
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A geneological study made it possible to establish a link between two medullary thyroid carcinoma families from Normandy totalling 9 sick subjects, and a probable link with a third family. The study contributed to the diagnosis of multiple endocrine neoplasia type IIa, whereas the condition had been diagnosed for 6 years as familial medullary thyroid carcinoma, without phaechromocytoma. Group in these two families together increased the number of subjects tested, thereby facilitating genetic link analysis and enabling the link with markers of the disease on chromosome 10 to be asserted. The genetic study can now be used to detect individuals at risk, and with regular laboratory tests the diagnosis will be made at the "precancerous" stage. A genealogical study going back to the family-founding couple will increase the population which will benefit from screening in this region north of Rouen.
The syndrome of multiple endocrine neoplasia type 2B (MEN 2B) resembles that of MEN 2A in that both include medullary carcinoma of the thyroid, pheochromocytoma, and autosomal dominant inheritance, but is distinct in that MEN 2B patients have neuromas of the mucous membranes. MEN2A has been linked to RBP3, D10S5, FNRB, D10S15, and D10Z1 near the centromere of chromosome 10. We examined linkage between MEN2B and RFLPs on chromosome 10 in all available members in two or three generations of 14 kindreds. The centromere marker D10Z1 was linked to MEN2B with a peak lod score of 5.42 at theta = 0.02. One possible recombinant was observed between D10Z1 and MEN2B. Multipoint analysis of RFLPs at FNRB, D10Z1, RBP3, and D10S15 gave a peak lod score of 7.12 at the midpoint between D10Z1 and RBP3 on the long arm (band q11). The most likely gene order FNRB-D10Z1-MEN2B was 27 times more likely than MEN2B-FNRB-D10Z1 and 31/2 times more likely than FNRB-MEN2B-D10Z1. Additional data will be required to establish the order of these loci with confidence.
Multiple endocrine neoplasia type 2a has been shown to be genetically linked to a locus near the centromere of chromosome 10. The availability of polymorphic DNA probes for the region permits the use of restriction-fragment-length polymorphisms (RFLP) to identify carriers of the gene for this cancer syndrome. As part of a French national program, DNA probes were used in a genetic-linkage study of 130 members of 11 families of European and North African origin. In these families there was no recombination between the mutation causing multiple endocrine neoplasia type 2a and two of the three probes used. All 11 families were informative for at least one of the three markers, and linkage information was adequate to provide genetic counseling to 8 families. We found that RFLP analysis is much more useful in predicting the carrier state than conventional endocrine challenge, especially in younger people, but accuracy is maximal when both methods are employed. We conclude that genetic screening allows the identification of those who are at risk for multiple endocrine neoplasia type 2a at any age with a high level of certainty. After initial screening with DNA, tests for early neoplastic change may be directed toward those determined to be at high risk.
The use of polymorphic DNA segments as markers for the gene for the multiple endocrine neoplasia (MEN) syndrome, type 2a, allows the identification of family members at high risk for developing medullary carcinoma of the thyroid and other tumors, especially pheochromocytoma. Several families have also been identified in which medullary thyroid carcinoma is inherited, but pheochromocytoma is not seen. We have analysed 18 families, 9 with MEN 2A and 9 with medullary carcinoma of the thyroid without pheochromocytoma, with probes specific for the pericentromeric region of chromosome 10 and conclude that the mutations for the two presentations are closely situated. Genetic heterogeneity of the susceptibility locus was not seen among this sample of 18 families. The genetic mutation for medullary carcinoma was in disequilibrium with the marker alleles of the two closely linked probes, IRBPH4 and MCK2. These data suggest that different mutant alleles of the same gene or closely linked mutations account for the variation in penetrance of pheochromocytoma in families with hereditary medullary thyroid carcinoma.
The inherited cancer syndrome multiple endocrine neoplasia type 2A (MEN2A) has recently been mapped to chromosome 10. We have typed 29 families with this disorder with DNA markers from the pericentromeric region of chromosome 10. Two markers, RBP3 and MCK2, were tightly linked to the MEN2A gene at recombination fractions of less than 3%. Multipoint analysis of the linkage data suggests that the gene is located within a 3-cM interval defined by the markers RBP3/MCK2 on one side and TB14.34 on the other. No evidence for locus heterogeneity was detected in any of the 27 families from 14 countries who were informative for the markers tested. The data confirm and refine the original assignment and provide the basis for presymptomatic screening for this disorder.
Multiple endocrine neoplasia type 2A (MEN2A) is an autosomal-dominant syndrome characterized by medullary thyroid carcinoma (MTC), pheochromocytoma and parathyroid hyperplasia. Recent reports have assigned the locus of MEN2A to the pericentromeric region of chromosome 10. Through the 'Groupe d'Etude des Tumeurs à Calcitonine', we have evaluated the ability to predict the carrier state using DNA probes. Our results suggest that the restriction fragment length polymorphism method can be used to identify individuals at risk within MEN2A families. They may then be followed by conventional endocrine methods for the onset of neoplastic changes, limiting the risk of subsequent metastatic disease. The method also permits the exclusion of further screening for family members at very low risk. Extension of the screening program can now be anticipated for other inherited forms of MTC, such as familial MTC without pheochromocytoma or other endocrinological tumor syndromes such as MEN1 for which the locus has also recently been mapped.
We have performed linkage analysis on 32 families with hereditary medullary thyroid cancer (MTC) with seven polymorphic DNA probes situated near the centromere of chromosome 10. Nineteen of these families were affected with multiple endocrine neoplasia type 2A (MEN 2A), and the remainder had MTC without pheochromocytoma. There were no instances of recombination between the MEN 2A susceptibility gene and the IRBP.H4 marker. Two other probes, TB14.34 and MCK2, are also tightly linked (theta = 0.00 and theta = 0.02, respectively). Because TB14.34 and IRBP.H4/MCK2 are situated on opposite sides of the MEN 2A gene, screening with flanking DNA markers is now feasible.
Hereditary medullary thyroid carcinoma (MTC) appears in three forms: 1) in association with pheochromocytomas and parathyroid hyperplasia (multiple endocrine neoplasia type 2A [MEN 2A]); 2) with pheochromocytomas, neuromas of the mucous membranes, and a marfanoid appearance (MEN 2B); and 3) without pheochromocytoma. Despite these differences in presentation, age of onset, and clinical severity, limited genetic studies suggest that the three MTC variants may be due to inherited mutations at the same gene locus. We present further data in support of the hypothesis that allelic variation may underlie the diversity of these endocrine neoplasia syndromes.
In a large kindred with multiple endocrine neoplasia type 2a (MEN 2a) (137 members, 5 generations), bilateral thyroid medullary carcinoma was found in all affected members. Pheochromocytoma was present in 59% of the cases, and was responsible at least for 4 out the 5 deaths related to MEN 2a. Hyperparathyroidism was less frequent (41%). Family screening leads to a reduction in age for diagnosis and to an improvement in the prevalence of complete healing after surgery. Linkage between HLA loci and a dominant gene for MEN 2a was investigated in this kindred. Lod scores for recombination fraction were all negative (-0.47 for a recombination fraction of 0.05). These results comfort the lack of linkage between MEN 2a and the HLA complex.
Due to the technical difficulties involved in identifying BRCA1/2 genetic mutations, the affected patients have to be investigated before testing can be made available to all the relatives at risk. Here, we studied the attendance rates at cancer genetic clinics (CGC) and the uptake of genetic testing in first/second degree relatives after the first BRCA1 mutated woman with cancer had been informed in the family. We carried out a survey on French cancer geneticists involved in breast/ovarian CGC, asking them to select their first three BRCA1 family records. Data collection was carried out retrospectively by telephone interview with a standardised closed item questionnaire. Considering only those families (n = 37) where the index case had been informed for at least 8 months at the time of the survey, the overall attendance at CGC of first/second degree relatives (n = 419) was 31.7% (n = 133) and the overall uptake of BRCA1 testing was 26.7% (n = 112). Among those who attended the CGC (n = 133), 84.2% (n = 112) requested genetic testing (95% confidence interval: 78-90.4%). Among the first degree relatives, the unaffected women who attended accounted for 59.8% and 51.2% requested testing after the index case had been informed. Women with cancer had a higher attendance rate (83.3%) than unaffected women (36.1%) (Odds Ratio (OR) = 8.86; p < 0.001) and first degree relatives (51.4%) than second degree relatives (17.9%) (OR = 2.87; p < 0.001); women (43%) also attended more frequently than men (16%) (OR = 3.97, p < 0.001). In French BRCA1 mutated families, female first degree relatives of the index patient show the most interest in genetic testing.
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The aim of this study was to investigate the effects of cancer genetic consultations on feelings of anxiety in women with breast/ovarian cancer. Among the 138 women attending six French clinics during a one-year period, 115 (83.3%) answered pre- and post-consultation questionnaires. The state anxiety score (Spielberger's STAI) was lower (paired t-test, p<0.001) after the consultation (34.7 9.4) than before (38.8 10.5). The time elapsing since cancer diagnosis (r=-0.28, p=0.007) was the main predictor of the decrease in anxiety. The patients consulting earlier after their cancer was diagnosed were more anxious before the consultation than those consulting later: whereas their anxiety states after the consultation were similar. The consultation effectively decreased the anxiety observed and the anxiety felt by cancer patients before the consultation may constitute an anticipatory stress response that should be investigated.
Cancer results from the accumulation of selected mutations. We propose here that some combinations of mutations may be counterselected. To illustrate this, we show an analysis of allelotyping in human breast tumors in which we demonstrate that specific associations of genetic events are statistically under-represented. This emerging concept could be used in a new therapeutical approach of cancer.
BACKGROUND: PS2-expression is controlled by estrogens and is a prognostic factor for long-term and post-relapse survival. Breast carcinomas associated with a BRCA1 mutation (BRCA1-BC'S) exhibit many specific features, particularly for ER expression. Our purpose was to determine if pS2-expression was different in BRCA1-BC's compared with sporadic breast cancers. MATERIALS AND METHODS: We studied, by immunohistochemistry pS2-cxpression in a series of 33 BRCA1-BC's and a series of 193 sporadic cases according to many parameter including hormone receptors (ER and PR). RESULTS: In BRCA1-BC's, pS2 was expressed in only 10/33 (30.3%) carcinomas, and 4/4 (100%) ER positive: among sporadic carcinomas, 133/193 (68.9%) cases were pS2-positive, 102/127(80.37%) ER positive; the difference was significant (p<0.0001). In univariate analysis, pS2-expression was correlated with many parameters including hormonal receptor status and absence of BRCA1 mutation. In multivariate analysis, pS2-expression was still correlated with ER but no more with BRCA1 mutation. CONCLUSION: pS2-expression in BRCA1-BC's was significantly different from sporadic breast cancer (p<0.0001) and correlated in a multivariate analysis with the same factors in sporadic and BRCA1-BC's but not with BRCA1 mutation.