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I Schuffenecker

Publications and source records attributed to I Schuffenecker.

31 records · Page 2Linked to original sources
PubMed1995

RET mutations in exons 13 and 14 of FMTC patients.

RET is a receptor tyrosine kinase gene which is responsible for three different inherited cancer syndromes namely multiple endocrine neoplasia type 2A (MEN 2A), type 2B (MEN 2B) and familial medullary thyroid carcinoma (FMTC) as well as for Hirschsprung disease (HSCR), a congenital disorder affecting the intestinal motility. Germ-line mutations in the RET exons 10 and 11 were demonstrated in the majority of the MEN 2A and FMTC patients. On the other hand, one codon of RET exon 16 is preferentially changed in MEN 2B patients. Recently, a germ-line mutation in the exon 13 was described in one FMTC family as well as in four sporadic MTCs. In the present study, we observed the same exon 13 mutation in two FMTC families. In addition, we identified a previously unreported substitution of RET exon 14 in two unrelated FMTC families. Both mutations segregate with the disease in these four FMTC families and involve the tyrosine kinase domain of RET. Haplotype analysis using polymorphic markers tightly linked to the RET gene indicates that in each pedigree the mutation arose as an independent event.

Adult↗
PubMed1995

Detection of a germline mutation at codon 918 of the RET proto-oncogene in French MEN 2B families.

Multiple endocrine neoplasia type 2A (MEN 2A), type 2B (MEN 2B), and familial medullary thyroid carcinoma (FMTC) are three dominantly inherited disorders linked to the same disease locus on chromosome 10. Two types of germline mutation of the RET proto-onco-gene, which codes for a transmembrane tyrosine kinase, are associated with MEN 2. Missense mutations at cysteine residues in the extra-cytoplasmic domain are exclusively associated with MEN 2A and FMTC. In MEN 2B patients, a single point mutation at codon 918 has recently been characterized, leading to the replacement of a methionine by a threonine within the RET tyrosine kinase domain. We now report the identification of a mutation at codon 918 in the germline of 16 patients out of 18 unrelated MEN 2B families analyzed. In these families we have been able to demonstrate that, in five cases, the mutation arose de novo, and that, in one kindred, it was coinherited with the disease. These results indicate that a unique mutation at codon 918 of the RET gene is the most prevalent genetic defect causing MEN 2B, but also that rare MEN 2B cases are associated with different mutations yet to be defined.

Adolescent↗
PubMed1995

Genotype-phenotype correlation in multiple endocrine neoplasia type 2: report of the International RET Mutation Consortium.

The International RET Mutation Consortium was first convened as part of the Fifth International Workshop on Multiple Endocrine Neoplasia, Stockholm, Sweden, in an attempt to analyse the relationship of RET mutation and disease phenotype in the autosomal dominantly inherited multiple endocrine neoplasia type 2 (MEN 2) syndromes. Out of 361 families studied, 41% had MEN 2A, 17.7% MEN 2B, 6.4% FMTC and the remaining subjects were unclassified. RET mutations were detected in 87.3% of families overall. Over 93% of MEN 2B families had the RET 918 ATG-->ACG mutation, while the most frequent mutation detected in MEN 2A families was cysteine codon 634 (87% of all mutations).

Carcinoma, Medullary↗
PubMed1994

RET proto-oncogene mutations in French MEN 2A and FMTC families.

Constitutional mutations of the RET proto-oncogene have been identified in multiple endocrine neoplasia type 2A (MEN 2A), type 2B (MEN 2B) and familial medullary thyroid carcinoma (FMTC) families. We sequenced RET exons 10 and 11 in 86 unrelated patients with an inherited predisposition to MTC (excluding MEN 2B). Germ-line mutations were identified in 93% of the MEN 2A families and 67% of the FMTC families tested. All were missense mutations affecting one of three cysteines in the extracellular domain of the RET tyrosine kinase receptor. The prevalence of phaeochromocytoma and hyperparathyroidism was significantly higher in families with a mutation of cysteine 634. These data confirm the preferential localisation of MEN 2A and FMTC associated mutations and the strong correlation between clinical manifestations and the position of RET mutation. Although direct sequencing of RET exons 10 and 11 allows the identification of a constitutional mutation in a large proportion of MEN 2A and FMTC families, our data sustain the existence of other MTC predisposing mutations elsewhere in RET coding or regulating region.

Carcinoma, Medullary↗
PubMed1994

Pentagastrin stimulation test and early diagnosis of medullary thyroid carcinoma using an immunoradiometric assay of calcitonin: comparison with genetic screening in hereditary medullary thyroid carcinoma.

A pentagastrin stimulation test using a calcitonin (CT) immunoradiometric assay was performed in 38 healthy subjects and in the following 50 patients: 25 subjects from families with at least 2 known cases of medullary thyroid carcinoma (MTC), 11 subjects from families with apparently sporadic MTC, 2 pheochromocytoma carriers, 1 primary hyperparathyroidism, 8 patients with thyroid nodules, and 3 others with various diseases. In healthy volunteers, basal CT values were always less than 10 ng/L; the response to pentagastrin was below 30 ng/L for 36, and for the remaining 2, the peaks reached 30 for 1 subject and 48 ng/L for the other. The pentagastrin-stimulated CT peak was above 30 ng/L in each of the patients presented here, and all were thyroidectomized. In screening the 25 relatives of patients with familial MTC, a CT peak level over 30 ng/L was constantly associated with C-cell disease (23 cases of MTC and 2 of C-cell hyperplasia). A response to pentagastrin above 100 ng/L was observed in 15 patients among the 23 with MTC. In 8 of the 10 patients with a peak CT level between 30-100 ng/L, pathological examination showed a MTC; the other 2 had C-cell hyperplasia and a negative linkage study analysis. In the 25 other patients in the study without familial MTC, the pentagastrin-stimulated CT level was over 100 ng/L in 11 of the 14 subjects with MTC. The abnormal CT response to pentagastrin, which has been used as a criterion for surgical treatment, is currently determined by an immunoradiometric assay. Our study confirms that subjects with a peak CT level above 100 ng/L should undergo surgery whatever the reason for the test. In the context of inherited MTC, our results suggest that for patients with a CT peak level between 30-100 ng/L, surgery may actually be postponed when their probability of being gene carriers is low. Recent progress with the characterization of specific mutations in affected individuals will make familial screening much easier in the next few months.

Adolescent↗
PubMed1993

Evaluation of four commercial systems for identification of medically important yeasts.

Four commercially available systems for identification of yeasts were evaluated using 178 clinical isolates and seven reference strains previously identified by a conventional method. After 72 h of incubation, the rate of correct identification was 86.5% with API20C Aux, 86% with Auxacolor, 68% with Mycotube and 51.1% with Candifast. When considering only the reference strains included in the manufacturers' databases, the identification rate was 90%, 91%, 87% and 61.2% respectively. Although the results at 72 h obtained with API20C Aux and Auxacolor were similar, Auxacolor led to more rapid identification of the strains, 67.9% versus 14.6% being identified at 24 h and 80.9% versus 64% being identified at 48 h.

Evaluation Studies as Topic↗
PubMed1992

The genetics of multiple endocrine neoplasia (MEN).

Multiple Endocrine Neoplasia (MEN) refers to the family of diseases characterized by hyperplasia and/or tumoral proliferation in various organs derived from the neural crest. MEN are transmitted in an autosomal dominant fashion in affected pedigrees with a high degree of penetrance. MEN 1 and MEN 2A/B loci have recently been mapped, respectively, to chromosomes 11 and 10 by linkage analysis using polymorphic DNA markers. These discoveries will lead (1) to a rapid understanding of the physiopathological pathway determining such syndromes and (2) to major clinical impact through the genetic screening.

Chromosome Mapping↗
PubMed1991

The gene for mannose-binding protein maps to chromosome 10 and is a marker for multiple endocrine neoplasia type 2.

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.

Biomarkers, Tumor↗
PubMed1989

Early detection of hereditary medullary thyroid cancer with polymorphic DNA probes. Groupe d'Etude des Tumeurs a Calcitonine.

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.

Adrenal Gland Neoplasms↗
PubMed1989

Hereditary medullary thyroid carcinoma: genetic annalysis of three related syndromes. Groupe d'Etude des Tumeurs a Calcitonine.

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.

Adrenal Gland Neoplasms↗