Expression of Ro/SS-A and La/SS-B determined by immunohistochemistry in healthy, inflamed and autoimmune diseased human tissues: a generalized phenomenon.

OBJECTIVE: Autoantibodies to the ribonucleoproteins Ro/SS-A and La/SS-B are found in autoimmune diseases such as primary Sjögren's syndrome (pSS), systemic lupus erythematousus and rheumatoid arthritis. Increased and aberrant expression of Ro/SS-A and La/SS-B in target organs, which have been reported in the recent literature, might contribute to their antigenicity. However, data on the expression of Ro/SS-A and La/SS-B in other inflammatory conditions are scarce. MATERIALS AND METHODS: Using monoclonal antibodies against Ro/SS-A and La/SS-B, we studied the expression of these antigens in paraffin-embedded healthy tissue, aspecific inflamed tissue, the neonatal and adult cardiac conduction systems and labial salivary gland tissues of patients suspected of having pSS. RESULTS: In healthy tissues, the nuclei expressed both Ro/SS-A and La/SS-B. This expression was stronger in inflamed tissues. Nucleoli were negative and cytoplasmic expression was weaker than nuclear expression. No increased or aberrant expression of Ro/SS-A or La/SS-B was observed in either neonatal or adult atrioventricular nodes and bundle branches. More pSS patients showed high La/SS-B immunoreactivity levels in their labial salivary gland ductal cell nuclei than non-Sjögren's syndrome sicca patients. CONCLUSIONS: Ro/SS-A and La/SS-B expression is a generalized cell biological phenomenon and may be upregulated by increased cell activation both in aspecific and autoimmune-mediated inflammation. In pSS the high expression of La/SS-B in labial salivary, gland ductal cell nuclei might contribute to the local immune response.

[Lump in the neck: 4 patients with a medullary thyroid carcinoma]. / Een knobbeltje in de hals: 4 patiënten met een medullair schildkliercarcinoom.

In a 25-year-old man, medullary thyroid carcinoma (probably a solitary sporadic form) was diagnosed following investigation of a small lump in the patient's neck. This was removed and followed up with further treatment. In a 27-year-old man, episodes of headache, palpitations and excessive perspiration (due to a pheochromocytoma) and a positive family history of thyroid problems led to further investigations and the subsequent diagnosis of multiple endocrine neoplasia (MEN) type 2A. The patient died at 48 years of age as the result of liver metastases. A total thyroidectomy had been carried out on a 19-year-old man with familial medullary thyroid carcinoma. The calcitonin levels remained elevated, but no tumour residues could be found. A 16-year-old girl with MEN type 2B had also previously undergone surgery. Her main complaint consisted of persistent constipation. Thyroid carcinomas usually present as a nodule in the neck. In 25% of cases, medullary thyroid carcinoma is part of the MEN2 syndrome. The clinical approach for medullary thyroid carcinoma is based on pathological findings following fine needle aspiration biopsy. The results of DNA tests determine the course of treatment and the need for family testing. In families with a hereditary form, there is a clear genotype-phenotype correlation. Early diagnosis and treatment can improve life expectancy.

[Islet amyloid and diabetes mellitus type 2]. / Eilandjesamyloïd en diabetes mellitus type 2.

Type 2 diabetes mellitus is a heterogeneous and multifactorial disorder accompanied by severe complications and a reduced life expectancy. Histopathologically, it is characterized by deposition of protein in the islets of Langerhans in the pancreas ('islet amyloid'). The 37 amino acids 'islet amyloid polypeptide' (IAPP) was discovered in 1986 as the building block of islet amyloid. The identification of IAPP caused an intensification of research on islet amyloid. In the past few years, particularly transgenic mouse technology has shown that islet amyloidosis is a consequence as well as an (additional) cause in the pathogenesis of type 2 diabetes. Islet amyloid has turned out to be a pathogenic factor, which is accompanied by death of beta-cells and reduction of the insulin producing capacity. This knowledge offers opportunities for the development of novel (preventive) therapy and thus for a better life expectancy of persons which develop type 2 diabetes.

Long-term effects of corticosteroid nasal spray on nasal inflammatory cells in patients with perennial allergic rhinitis.

BACKGROUND: The effect of long-term topical nasal corticosteroid therapy on nasal inflammatory cells is unclear. OBJECTIVES: To investigate the long-term effect of fluticasone propionate aqueous nasal spray (FPANS) on nasal mucosal inflammatory cells and efficacy in a 1-year study in patients with perennial allergic rhinitis. METHODS: In a 1-year, double-blind, placebo-controlled study of duration we investigated the influence of a topical corticosteroid (FPANS), on Langerhans' cells (CD1a+ cells), T cells, mast cells, eosinophils and macrophages in nasal mucosa in 42 patients with perennial allergic rhinitis. Efficacy was evaluated by nasal symptom score. RESULTS: The FPANS group experienced significantly less sneezing and nasal itching compared with the placebo group. The total symptom score in the FPANS group declined significantly in comparison with baseline (P = 0.007) and placebo group (P = 0.009). After 1 year of active treatment, a significant decrease was seen in the epithelium in numbers of Langerhans' cells, CD3+, CD4+, CD8+ cells, mast cells and eosinophils. In the lamina propria, there was a significant decrease in eosinophils. CONCLUSION: These findings show that FPANS treatment results in a decrease of nasal inflammatory cells. Furthermore, the efficacy of FPANS improves after prolonged treatment.

A patient with neurofibromatosis type 1 and watery diarrhoea syndrome due to a VIP-producing adrenal phaeochromocytoma.

A patient with neurofibromatosis type 1 and watery diarrhoea syndrome due to a VIP-producing adrenal phaeochromocytoma (Case Report). J Intern Med 1999; 246: 231-234. A 43-year-old patient with neurofibromatosis type 1 suffered from watery diarrhoea syndrome induced by excessive production of vasoactive intestinal polypeptide (VIP) in an adrenal phaeochromocytoma. This case report emphasizes that patients with neurofibromatosis are prone to develop more than one disease induced by tumours originating from the neural crest. Since excessive VIP production in a phaeochromocytoma may mask the symptoms of catecholamine overproduction, and in view of the therapeutic consequences, neurofibromatosis patients with hyperVIP-aemia must be checked for the presence of a phaeochromocytoma.

[Women and part-time employment in the medical profession]. / Vrouwen en deeltijdarbeid in het medische beroep.

During a conference of this journal the following matters were raised: (a) part-time work in medicine, although generally accepted socially for men and women is not precisely advisable for those who want to move up to higher functions; (b) owing to the long duration of medical studies, physicians are late to marry and raise a family; (c) the ambition of medical women, amply present at the medical finals, often proves to extend no further than pregnancy; (d) the career of female doctors shows a kink caused mostly by family duties and inadequacy of day nurseries; (e) the current excessive workload of (senior) medical functionaries reduces many women's ambition to attain such functions. Women who want to study medicine should consider much earlier than is nowadays the case what they want and can become within the limits of their possibilities in the wide field of medicine. Energetic striving for shortening of the training period may result in earlier fulfilment of the wish to have children.

Extensive islet amyloid formation is induced by development of Type II diabetes mellitus and contributes to its progression: pathogenesis of diabetes in a mouse model.

AIMS/HYPOTHESIS: Type II (non-insulin-dependent) diabetes mellitus is a multifactorial disease in which pancreatic islet amyloid is a characteristic histopathological finding. Islet amyloid fibrils consist of the beta-cell protein "islet amyloid polypeptide" (IAPP)/"amylin". Unlike human IAPP (hIAPP), mouse IAPP cannot form amyloid. In previously generated transgenic mice, high expression of hIAPP as such did not induce islet amyloid formation. To further explore the potential diabetogenic role of amyloidogenic IAPP, we introduced a diabetogenic trait ("ob" mutation) in hIAPP transgenic mice. METHODS: Plasma concentrations of IAPP, insulin and glucose were determined at 3.5 (t1), 6 (t2), and 16-19 months of age (t3). At t3, the mice were killed and the pancreas was analysed (immuno)histochemically. RESULTS: In non-transgenic ob/ob mice, insulin resistance caused a compensatory increase in insulin production, normalizing the initial hyperglycaemia. In transgenic ob/ob mice, concurrent increase in hIAPP production resulted in extensive islet amyloid formation (more often and more extensive than in transgenic non-ob/ob mice), insulin insufficiency and persistent hyperglycaemia: At t3, plasma insulin levels in transgenic ob/ob mice with amyloid were fourfold lower than in non-transgenic ob/ob mice (p < 0.05), and plasma glucose concentrations in transgenic ob/ ob mice were almost twofold higher (p < 0.05). In addition, the degree of islet amyloid formation in ob/ob mice was positively correlated to the glucose:insulin ratio (r(s) = 0.53, p < 0.05). CONCLUSION/INTERPRETATION: Islet amyloid is a secondary diabetogenic factor which can be both a consequence of insulin resistance and a cause of insulin insufficiency. [Diabetol

Overexpression of c-Src enhances cell-matrix adhesion and cell migration in PDGF-stimulated NIH3T3 fibroblasts.

c-Src is normally associated with the plasma membrane, but upon activation by tyrosine kinase receptors it translocates to the cytoskeleton. Activation of c-Src alters its conformation and induces the association of c-Src with cytoskeletal proteins. c-Src is implicated in tyrosine phosphorylation of cytoskeletal proteins, which might affect the cytoskeletal architecture. Rearrangements of the cytoskeleton affect cell-matrix adhesion and cell migration. In this study NIH3T3 fibroblasts, that overexpress c-Src, were used to analyze the effect of c-Src on both cell-matrix adhesion and cell migration. Upon PDGF stimulation translocation of c-Src to the cytoskeleton was detected. PDGF treatment also increased cell-matrix adhesion and cell migration. The cell line with the highest c-Src expression showed the largest increases in both phenomena. These findings suggest that translocation of c-Src to the cytoskeleton results in enhanced cell-matrix adhesion and cell migration.

[Prophylactic total thyroidectomy in childhood for multiple endocrine neoplasia type 2A: preliminary results]. / Profylactische totale thyreoïdectomie voor multipele endocriene neoplasie type 2A op de kinderleeftijd: eerste ervaringen.

OBJECTIVE: Evaluation of prophylactic total thyroidectomy in childhood in case of MEN2A gene carriership. DESIGN: Retrospective. METHOD: Prophylactic thyroidectomy was performed in 14 MEN2A gene carriers (7 boys, 7 girls; median age 9.1 year (range: 4.8-14.7)), in June 1993-July 1997 at the department Pediatric Surgery of the Wilhelmina Children's Hospital in Utrecht, the Netherlands. Median time between genetic investigation and operation was 5.5 months (range: 2-35). Lymph node dissection was not performed. The parathyroids were identified and left untouched as far as possible, autotransplantation was performed twice because of doubt about viability. Outpatient follow-up took place every 3-6 months. RESULTS: One patient (13.4 year) showed macroscopic, the other 13 microscopic multifocal medullary thyroid carcinoma, 11 bilateral and 3 unilateral. In 1 child (6.2 year) neuroinvasive growth existed already. Surgical sections were free of tumour. After the operation temporary hoarseness occurred once, temporary hypocalcaemia three times and permanent hypoparathyroidism twice; after autotransplantation no hypocalcaemia occurred. Median follow-up was 3.2 year (range: 1 month-4.0 year). Mild psychological problems were observed in 4 patients, psychiatric problems in 1. CONCLUSION: Prophylactic total thyroidectomy during the first decade is recommended. Additional lymph node dissection and total parathyroidectomy are unnecessary than. In order to prevent postoperative hypoparathyroidism, autotransplantation of at least one parathyroid is advisable.

Islet amyloid polypeptide/amylin messenger RNA and protein expression in human insulinomas in relation to amyloid formation.

OBJECTIVE: Islet amyloid polypeptide (IAPP), also named amylin, is the predominant protein component of amyloid deposits in human islet beta cell tumours of the pancreas (insulinomas). IAPP is co-produced with insulin by islet beta cells. We investigated IAPP expression in relation to insulin expression and to amyloid formation in eleven insulinomas. DESIGN AND METHODS: RNA and protein extracts were prepared from the same pieces of tumour tissue, and from specimens of two normal human pancreata. IAPP and insulin mRNA and peptide content were quantified using Northern blot analysis and radioimmunoassay (RIA) respectively. Molecular forms of IAPP immunoreactivity were analysed by reversed-phase high-performance liquid chromatography (HPLC). The presence of islet hormones and of amyloid was assessed by (immuno)histochemical staining of paraffin sections. Plasma levels of IAPP and insulin prior to tumour resection were determined by RIA. RESULTS: IAPP and insulin mRNA and peptide content varied widely between the tumour specimens, and there was considerable intratumour heterogeneity of peptide content. HPLC analysis indicated correct proteolytic processing of the IAPP precursor protein. Amyloid deposits were detected only in the three tumours with the highest IAPP content. In contrast to insulin, plasma levels of IAPP were not elevated in the insulinoma patients. CONCLUSIONS: The spectrum of hormone production by insulinomas cannot be inferred from only a few tissue sections due to intratumour heterogeneity. Expression of the IAPP and insulin genes is not coupled in insulinomas, which produce properly processed mature IAPP. In addition to IAPP overproduction, additional factors such as intracellular accumulation of IAPP are involved in amyloidogenesis in insulinomas.

In vivo experiments with mesothelial cell seeded ePTFE vascular grafts.

OBJECTIVES: To investigate the influence of mesothelial cell (MC) seeding on patency and neointimal formation of small diameter ePTFE grafts in a canine model. MATERIALS AND METHODS: MC were isolated from the omentum, cultured, seeded on fibronectin-coated ePTFE grafts (4 cm, 4 mm ID), and implanted in the carotid artery of five Beagle dogs. Each dog also received a non-seeded control graft. Patency was assessed by palpation immediately after implantation, and non-invasively by magnetic resonance angiography (MRA) after 1 week and just prior to sacrifice (4 weeks). Intimal thickness was quantified on histological sections by use of computer-aided morphometry. RESULTS: All grafts were patent after implantation. After 1 week, MRA showed the loss of lumen diameter in two seeded grafts. After 4 weeks, two seeded grafts were occluded, one seeded graft was severely stenosed, and all others were without angiographic lumen reduction. Histology and morphometry confirmed that two seeded grafts were occluded, and demonstrated that the other three seeded grafts showed significantly more intima formation (0.22-1.34 mm) than the control grafts (< 0.08 mm; p < 0.01). CONCLUSIONS: The MC seeding process decreases patency and increases neointimal formation of small diameter ePTFE grafts in dogs and does not seem to be useful for reduction of graft thrombogenicity.

A 1-year placebo-controlled study of intranasal fluticasone propionate aqueous nasal spray in patients with perennial allergic rhinitis: a safety and biopsy study.

In a 1-year, placebo-controlled, double-blind, randomized study the long-term effect of Fluticasone Propionate Aqueous Nasal Spray (FPANS) in 42 patients with a perennial allergic rhinitis was studied with regard to safety and efficacy. Twenty-nine patients completed the entire treatment period. After 1 year of treatment no deleterious changes consequent on therapy were observed in nasal mucosal biopsies. The appearance of the epithelial layer, the degree of cellular infiltration, the extent to which the sinusoids were dilated and the degree of tissue oedema improved or remained unchanged in 93% of the patients of the FPANS group, versus 75% of the placebo group, and worsened in 7% of the FPANS group versus 25% of the placebo group. Assessment of the changes in haematological, biochemical, urinary, plasma cortisol levels, and in the findings during nasal examination revealed no significant differences between the two treatment groups. After 1 year of treatment symptom scores for sneezing, nasal itching, and total symptom score were significantly better in the FPANS treated group (P < 0.05, P < 0.05, P < 0.01). An initial reduction in total symptom score was found after 4 weeks FPANS treatment with a further reduction after 8 months of FPANS treatment. These findings suggest that the maximum efficacy of topical intranasal steroids is reached after long-term treatment, and thus advocates longer usage before treatment is stopped because of presumed inefficacy.

Overexpression of EGFR and c-erbB2 causes enhanced cell migration in human breast cancer cells and NIH3T3 fibroblasts.

Overexpression of EGFR and c-erbB2 frequently occurs in human breast cancers, correlating with poor prognosis. Here we show that overexpression of EGFR and c-erbB2 in cell lines increases cell migration, an important step in metastasis formation. The effect of EGFR on migration is dependent on the addition of EGF to the cells. In contrast, c-erbB2 seems to act independently of its ligand in these assays. Overexpression of this receptor is sufficient to induce cell migration. In addition, we investigated the involvement of a number of signal transduction pathways known to be activated by the EGFR. We found that inactivation of MAPKK results in a decreased migration, while inactivation of PI3K increases migration.

Grb2 overexpression in nuclei and cytoplasm of human breast cells: a histochemical and biochemical study of normal and neoplastic mammary tissue specimens.

In 20-30 per cent of human breast cancers, the receptor tyrosine kinases epidermal growth factor receptor (EGFR) and c-erbB2 are overexpressed. This overexpression leads to increased mitogenic signalling and is correlated with poor prognosis. Overexpression of associated adaptor proteins, like Grb2, can also induce upregulation of signalling pathways. In this study, the expression of the Grb2 adaptor protein was determined in both normal human breast tissue and mammary cancers, using immunoblotting experiments and immunostaining on paraffin-embedded tissue sections. Both biochemical and immunohistochemical techniques revealed overexpression of Grb2 in all breast cancer specimens. In addition, although Grb2 protein is described as localized in the cytoplasm, it can also be detected in the nucleus, both in normal and in tumour breast tissue. In tumour breast tissue, 58 per cent of Grb2 protein is found in the nucleus, while 37 per cent is detected in the cytoplasm. In normal breast tissue, 22 per cent of Grb2 is found in the nucleus and 70 per cent in the cytoplasm. These findings indicate that in human breast cancer, Grb2 is overexpressed and appears to be predominantly localized in the nucleus.

[Retinoids: use in combating cancer]. / Retinoïden: toepassing bij de bestrijding van kanker.

Retinoids are a group of natural and synthetic analogues of vitamin A (retinol). The biological activity of retinoids is mediated by multiple nuclear receptors which bind to specific DNA sequences and regulate transcription of target genes. Retinoids affect cell growth and differentiation. Retinoids inhibit chemically induced carcinogenesis in experimental animals. Clinical application of retinoids is efficacious to different degrees in prevention and therapy of some malignancies in humans, such as promyelocytic leukaemia, notably in combination chemotherapy. Unfortunately, lack of response, recurrence, toxicity and resistance are observed. Worldwide clinical trials have been set up to evaluate the treatment of mammary carcinoma with retinoids. It appears important to determine, before starting treatment, whether oestrogen or retinyl receptors are present in the tumor tissue.

Progesterone receptors in arachnoid cysts. An immunocytochemical study in 2 cases.

We report 2 cases of arachnoid cysts, one with a retrocerebellar and the other with a left temporal localization, in which immunohistochemical studies had been conducted. The results of the immunohistochemistry on the presence of carcino-embryonic antigen (CEA) and glial fibrillary acidic protein (GFAP), and of the scanning- and transmission electron microscopy revealed the cyst lining to be identical to subdural neurothelium. Progesterone receptors were found in the nuclei of cells lining the cyst, which also suggests the similarity of the cyst lining to arachnoid granulations and meningiomas as derivatives of subdural neurothelium, which also possess progesterone receptors.

Immunohistochemical analysis of decalcified paraffin-embedded human bone marrow biopsies with emphasis on MHC class I and CD34 expression.

AIMS: To identify the stromal structures and haematopoietic cell lineages in normal bone marrow. The optimal conditions were studied for the reactivity of a panel of antibodies, applicable to paraffin sections of decalcified trephine biopsies using antigen retrieval methods. METHODS AND RESULTS: Two methods of antigen retrieval (pepsin and acid citrate buffer) were tested. For the demonstration of most antigens and for reduction of background staining, heating in acid citrate buffer was preferred. In the case of elastase and von Willebrand Factor (factor VIIIrAg) pepsin pre-treatment was optimal, whereas Ulex europaeus agglutinin (UEA-1) and alpha-smooth muscle actin (alpha-SMA) required no pretreatment. Staining patterns obtained after 48 h EDTA decalcification and short electrolytic decalcification were identical. Both methods allowed recognition of HLA-A and HLA-B antigens, isolated CD34+ cells, mono-histiocytic cells (CD68+), myeloid cells (elastase and myeloperoxidase), erythroid cells (glycophorin C) and of megakaryocytic cells (Factor VIIIrAg). A relative simple lymphocyte-subset analysis was possible in decalcified paraffin sections allowing recognition of B-cells (CD20+) and T-cells (CD3+ and CD45RO+) in frequencies comparable to frozen sections. Suitable stromal cell staining was achieved by vimentin and desmin antibodies, whereas the bone marrow capillary network was visualized by CD34, factor VIIIrAg and UEA-1. CONCLUSIONS: This immunohistochemical study indicates that all cellular components of the haematopoietic microenvironment of the bone marrow can be identified in decalcified paraffin sections using antigen retrieval methods and that the time of decalcification can be reduced to 1-1.5 h.

Thrombomodulin activity on mesothelial cells: perspectives for mesothelial cells as an alternative for endothelial cells for cell seeding on vascular grafts.

Lining the luminal surface of prosthetic small diameter bypasses with endothelial cells (EC) will lower its thrombogenicity. Unfortunately, human EC are scarce. Mesothelial cells (MC) may be a valuable alternative for EC, since they are abundantly available and have antithrombotic and fibrinolytic properties. An important anticoagulant function of EC is due to thrombomodulin (TM) on the surface. The presence of TM on omentally derived human MC is not known but would increase the chance of successful use of MC for cell seeding procedures. The expression and localization of TM on human MC was studied using monoclonal antibodies. TM activity on cultured MC, and the influence of cytokines, was measured by the generation of activated protein C (APC), and was compared to EC. TM is expressed on the surface of MC as well as intracellularly, both in vivo and in vitro. The TM-dependent generation of APC was significantly higher on cultured MC than on cultured EC (817 +/- 141 PM v 262 +/- 38 PM; P < 0.001); their reaction to cytokines was almost identical. Seeding the MC onto vascular prostheses did not change the TM activity. Thrombomodulin is present and highly active on cultured and seeded MC. This may have major implications for MC as a source for cell seeding on vascular prostheses.

c-Src protein expression is increased in human breast cancer. An immunohistochemical and biochemical analysis.

In human breast cancer, c-Src activity is elevated compared to normal breast tissue. It is not yet known whether this increase in c-Src activity is accompanied by an increase in c-Src protein expression. In this study, c-Src activity and protein expression were determined in a series of human breast cancers and in normal breast tissue, using immune complex kinase assays and immunoblotting. As the heterogeneity of breast cancer is not taken into account in these biochemical experiments, immunohistochemistry was also used to distinguish between normal and malignant cells. In human breast cancers, the c-Src activity is increased 4- to 30-fold, compared with normal breast tissue. This enhanced activity is accompanied by an increase in c-Src protein expression, as shown by both immunoblotting and immunohistochemistry. Immunohistochemistry indicates that the majority of c-Src appears to be concentrated around the nucleus in malignant cells, whereas in normal cells, it is distributed more evenly in the cytoplasm. These data confirm that c-Src activity is increased in human breast cancer. In addition, this study provides strong immunohistochemical evidence that the c-Src protein is also overexpressed, enabling a distinction to be made between normal and malignant cells.

Familial medullary thyroid carcinoma: not a distinct entity? Genotype-phenotype correlation in a large family.

BACKGROUND: Multiple endocrine neoplasia type 2A (MEN 2A) is a hereditary syndrome characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, and hyperparathyroidism. Familial MTC (FMTC) is characterized by MTC only. Both MEN 2A and FMTC are caused by germline mutations of the RET proto-oncogene. PURPOSE: To assess genotype/phenotype correlations, large families have to be examined periodically over a long period using an extensive screening program. PATIENTS AND METHODS: Since 1973, we screened a large family with hereditary C cell carcinoma for MTC, pheochromocytoma, and parathyroid disease by clinical tests and imaging methods. A germline codon Cys618 to Ser mutation in the RET proto-oncogene was recently identified in this family. The disease phenotype associated with this mutation was compared with that of Cys634 mutations in some other large MEN 2A families. RESULTS: The distinct course of disease in the family described here is similar to that in other FMTC families and MEN 2A families with a Cys618 mutation of the RET gene, but clearly different from that in families with a Cys634 mutation. The frequency of pheochromocytomas and parathyroid disease is clearly lower, whereas cure rates and life expectancy are higher. However, in families with a Cys618 mutation, pheochromocytoma and parathyroid disease do occur. CONCLUSION: In FMTC families with cysteine codon mutations of the RET proto-oncogene, screening for other endocrinopathies is mandatory, since these may not be MTC-only families. Therefore, we suggest that MEN 2A families should not be subclassified into MEN 2A and FMTC, but rather according to their specific mutation in the RET protein (i.e., for this family MEN 2A RET C618S).