Social, neurodevelopmental, endocrine, and head size differences associated with atypical deletions in Williams-Beuren syndrome.

Williams-Beuren syndrome (WBS) is a multisystem disorder caused by a hemizygous deletion on 7q11.23 encompassing 26-28 genes. An estimated 2-5% of patients have "atypical" deletions, which extend in the centromeric and/or telomeric direction from the WBS critical region. To elucidate clinical differentiators among these deletion types, we evaluated 10 individuals with atypical deletions in our cohort and 17 individuals with similarly classified deletions previously described in the literature. Larger deletions in either direction often led to more severe developmental delays, while deletions containing MAGI2 were associated with infantile spasms and seizures in patients. In addition, head size was notably smaller in those with centromeric deletions including AUTS2. Because children with atypical deletions were noted to be less socially engaged, we additionally sought to determine how atypical deletions relate to social phenotypes. Using the Social Responsiveness Scale-2, raters scored individuals with atypical deletions as having different social characteristics to those with typical WBS deletions (p = .001), with higher (more impaired) scores for social motivation (p = .005) in the atypical deletion group. In recognizing these distinctions, physicians can better identify patients, including those who may already carry a clinical or FISH WBS diagnosis, who may benefit from additional molecular evaluation, screening, and therapy. In addition to the clinical findings, we note mild endocrine findings distinct from those typically seen in WBS in several patients with telomeric deletions that included POR. Further study in additional telomeric deletion cases will be needed to confirm this observation.

Hiperparatiroidismo primario asociado a neoplasia endocrina múltiple tipo 1 (MEN 1). Experiencia en 71 casos / Primary hyperparathyroidism associated with MEN 1: Experience in 71 cases

INTRODUCCIÓN: El hiperparatiroidismo (HPT) asociado al MEN 1 se caracteriza por ser una afectación multiglandular, no afectándose todas las glándulas en el mismo momento. Suele ser asintomático, aunque la afectación ósea es elevada en los pacientes jóvenes. Las tasa de recidiva y persistencias es de 25-35%. Los objetivos fueron: a) estudiar HPT-MEN 1; y b) analizar las variables relacionadas con la presencia o no de clínica y con la persitencia. MÉTODO: De 97 sujetos con MEN 1 diagnosticados en el HUVA, Murcia, pertenecientes a 16 familias, se han estudiado restrospectivamente 71 pacientes con afectación paratiroidea. Las variables estudiadas son: mutación, edad de diagnóstico, clínica, los valores de calcio, fóforo y PTHi, MIBI, técnica quirúrgica, valores de la PTHi y tasa de recidiva. RESULTADOS: La edad media fue de 38 años, y 50 estaban asintomáticos en el momento del diagnóstico. La técnica quirúgica realizada fue: paratiroidectomía subtotal (n = 55), paratiroidectomía de 3 glándulas (n = 7) y resección de menos de 3 glándulas (n = 9). Se asoció timectomía transcervical en 53. El seguimiento medio ha sido de 102,9 meses. Se han encontrado 21 recidivas (10 cirugía incompleta). Encontramos una relación estadísticamente significativa entre: la edad de diagnóstico (p < 0,0005) y los valores elevados de calcio (p < 0,008) y la presencia de clínica en el momento del diagnóstico, la técnica quirúrgica incompleta (p < 0,003), no timectomía (p < 0,0001) y seguimiento (p < 0,001) y la recidiva tras la cirugía. CONCLUSIÓN: La realización de screening genético y clínico nos permite un diagnóstico en fase asintomática y tratamiento precoz, evitando así complicaciones secundarias a la evolución del HPT. La tasa de recidiva del HPT en el MEN 1 es elevada, siendo los factores de recidiva el tiempo de seguimiento y la técnica quirúrgica realizada

INTRODUCTION: Primary hyperparathyroidism (pHPT) in MEN 1 is characterized by multiglandular disease and early involvement of parathyroid glands at different times. Persistence and recurrence range from 25%-35%. The purpose was: a) to describe the experience and the treatment of patients with pHPT in MEN 1; b) to analyze the variables related with clinical presentation and recurrence. METHOD: A total of 97 patients with MEN 1 were diagnosed in a tertiary hospital. A retrospective analysis was made in patients with pHPT (n = 71). Study variables: age at diagnosis, mutation, clinical presentation, laboratory tests, surgical technique, and recurrence of HPT. RESULTS: Mean age was 38 years, and 50 patients were asymptomatic. The surgical technique was: subtotal parathyroidectomy (n = 55), resection of three glands (n = 7), and resection of less glands (n = 9). Transcervical thymectomy was performed in 53 patients. Mean follow-up was 102.9 months. There were 21 recurrences, There were correlations between age at diagnosis and serum calcium levels with the presence of symptoms (P < .0001). There were also correlations between recurrence and surgical technique (P < .03), non-association with thymectomy (P < .0001), and follow-up time (P < .03). CONCLUSION: Performing genetic and clinical screening allows us to make a diagnosis in the asymptomatic period and to provide early treatment for HPT in MEN 1. The recurrence rate is high, and follow-up time and the surgical technique used are risk factors for recurrence

Morphology, Biochemistry, and Pathophysiology of MENX-Related Pheochromocytoma Recapitulate the Clinical Features.

Pheochromocytomas (PCCs) are tumors arising from neural crest-derived chromaffin cells. There are currently few animal models of PCC that recapitulate the key features of human tumors. Because such models may be useful for investigations of molecular pathomechanisms and development of novel therapeutic interventions, we characterized a spontaneous animal model (multiple endocrine neoplasia [MENX] rats) that develops endogenous PCCs with complete penetrance. Urine was longitudinally collected from wild-type (wt) and MENX-affected (mutant) rats and outputs of catecholamines and their O-methylated metabolites determined by mass spectrometry. Adrenal catecholamine contents, cellular ultrastructure, and expression of phenylethanolamine N-methyltransferase, which converts norepinephrine to epinephrine, were also determined in wt and mutant rats. Blood pressure was longitudinally measured and end-organ pathology assessed. Compared with wt rats, mutant animals showed age-dependent increases in urinary outputs of norepinephrine (P = .0079) and normetanephrine (P = .0014) that correlated in time with development of tumor nodules, increases in blood pressure, and development of hypertension-related end-organ pathology. Development of tumor nodules, which lacked expression of N-methyltransferase, occurred on a background of adrenal medullary morphological and biochemical changes occurring as early as 1 month of age and involving increased adrenal medullary concentrations of dense cored vesicles, tissue contents of both norepinephrine and epinephrine, and urinary outputs of metanephrine, the metabolite of epinephrine. Taken together, MENX-affected rats share several biochemical and pathophysiological features with PCC patients. This model thus provides a suitable platform to study the pathogenesis of PCC for preclinical translational studies aimed at the development of novel therapies for aggressive forms of human tumors.

Laboratory approaches for the diagnosis and assessment of hypercalcemia.

Calcium, the fifth most common element in the body, plays major physiological functions. Measurement of blood calcium is one of the most commonly ordered laboratory tests in assessments of calcium homeostasis and disease diagnosis. Hypercalcemia is an increased level of calcium in the blood. This disorder is most commonly caused by primary hyperparathyroidism and malignancy. However, other less common causes of elevated calcium levels need to be considered when making a differential diagnosis. This review is intended to provide readers with a better understanding of calcium homeostasis and the causes and pathophysiology of hypercalcemia. Most importantly, this review describes useful approaches for laboratory scientists and clinicians to appropriately diagnose and assess hypercalcemia.

Neoplasias endocrinas múltiples: 2 casos de diagnóstico familiar y espontáneo / Multiple endocrine neoplasia: Familiar and spontaneous diagnosis

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Multiple endocrine neoplasia: the enigma of MEN.

Multiple endocrine neoplasia (MEN) is an array of tumors found in various endocrine glands throughout the human body. A wide spectrum of clinical manifestations accompanies this syndrome. The complexities of the glandular function and subtle development of symptoms can cause the diagnosis to be missed, and individuals with MEN can be an enigma to the care team. Appropriate differential diagnosis and assessment are critical for these individuals to receive optimal care. An interprofessional team of health care providers, including an endocrinologist and an advanced practice endocrine nurse, must work in concert to orchestrate a plan of care across the continuum. Those specialized nurses who encounter individuals with MEN in a critical care setting are positioned to support the patient, the family, and the care team through this maze of multiple endocrinopathies and tumors.

p27kip1: a new multiple endocrine neoplasia gene?

Multiple endocrine neoplasias (MEN) are autosomal dominant disorders characterized by the occurrence of tumors in at least two endocrine glands. Two types of MEN syndromes have long been known: MEN type 1 (MEN1) and MEN type 2 (MEN2), associated with a different spectrum of affected organs. MEN1 and MEN2 are caused by germline mutations in the MEN1 tumor suppressor gene and the RET proto-oncogene, respectively. Lately, a new type of MEN was identified (named MEN4) which is due to mutations in the CDKN1B gene, encoding for p27kip1 (p27), a cyclin-dependent kinase (Cdk) inhibitor that regulates the transition of cells from G1 to S phase. p27 is a non-canonical tumor suppressor since it is usually not somatically mutated in human cancers but it is often downregulated by post-translational mechanisms. The discovery of MEN4 has defined a new role for CDKN1B as a tumor susceptibility gene for multiple endocrine tumors. To date, six germline CDKN1B mutations have been found in patients with a MEN1-like phenotype but negative for MEN1 mutations. Due to the limited number of patients so far identified, the phenotypic features of MEN4 are not clearly defined. Here, we review the clinical and molecular characteristics of the MEN4 syndrome and summarize the main functions of p27 to better comprehend how their alteration can predispose to neuroendocrine tumors.

MEN syndromes.

MEN1 and MEN2 are rare inherited cancer syndromes which express a variety of endocrine and nonendocrine tumors. The improved knowledge of molecular and clinical physiopathology of MEN syndromes, together with the availability of genetic testing, have led to earlier detection and intervention, with consequent reduction of mortality and morbidity for MEN-associated tumors. Genetic testing has gained a key role in the detection of asymptomatic patients harbouring mutations responsible for these syndrome, and allows institution of early and tailored intervention with a positive impact on the course of disease.

Dermatologic manifestations of parathyroid-related disorders.

Dermatologic manifestations of parathyroid-related disorders, although rare in sporadic cases, are not uncommon in familial syndromes. Patients with familial hyperparathyroidism have several types of skin lesions. In multiple endocrine neoplasia 1, patients commonly have angiofibromas (85%) and collagenomas (70%), lesions that show loss of one 11q13 allele, the molecular abnormality in multiple endocrine neoplasia 1. They can also present with lipomas or café-au-lait spots. Cutaneous amyloidosis, an entity that can occur sporadically, has been described in multiple endocrine neoplasia 2a and is usually localized to the interscapular area. Metastatic calcification is an entity commonly encountered in patients with hyperparathyroidism and renal failure. It can be complicated by infections and necrosis. It is best treated by controlling hypercalcemia, hyperphosphatemia, hyperparathyroidism, antibiotics, and analgesia. Parathyroidectomy is reserved for refractory cases. Hypoparathyroidism presenting in the context of polyglandular failure type 1 is characterized by mucocutaneous candidiasis. Pseudohypoparathyroidism, an inherited disorder with end-organ unresponsiveness to parathyroid hormone, is characterized by Albright hereditary osteodystrophy. Patients present with short stature, round facies, brachydactyly, and short fourth or fifth metacarpals.

Rare syndromes.

Dermatologists may also encounter patients presenting with skin lesions that reflect an underlying endocrine disorder not commonly seen in daily practice. Some of these endocrine disorders include glucagonoma, neurofibromatosis type 1, McCune-Albright syndrome, multiple endocrine neoplasia, the Carney complex, carcinoid tumors, and mastocytosis. The clinical syndrome classically associated with glucagonoma includes necrolytic migratory erythema, weight loss, diabetes mellitus, anemia, cheilitis, venous thrombosis, and neuropsychiatric symptoms. The hallmarks of neurofibromatosis type 1 are the multiple café-au-lait spots and associated cutaneous neurofibromas. Other presenting features include freckling, peripheral neurofibromas, Lisch nodules, bone abnormalities, tumors, neurologic abnormalities and hypertension. McCune-Albright syndrome is characterized by café-au-lait spots, polyostotic fibrous dysplasia, sexual precocity, and hyperfunction of multiple endocrine glands. Multiple endocrine neoplasia type 2A is characterized by medullary thyroid cancer, pheochromocytoma, and primary parathyroid hyperplasia. In some patients with multiple endocrine neoplasia type 2A, cutaneous lichen amyloidosis may also be present. Multiple endocrine neoplasia type 2B is characterized by medullary thyroid cancer and pheochromocytoma but not hyperparathyroidism. The syndrome also includes mucosal neuromas, typically involving the lips and tongue, intestinal ganglioneuromas and a marfanoid habitus. Multiple endocrine neoplasia type 1 is an autosomal dominant predisposition to tumors of the parathyroid glands (four-gland hyperplasia), anterior pituitary, and pancreatic islet cells; hence, the mnemonic device of the "3 Ps"; multiple cutaneous lesions (angiofibromas and collagenomas) are frequent in patients with multiple endocrine neoplasia type 1. Carney complex may be viewed as a form of multiple endocrine neoplasia because affected patients often have tumors of two or more endocrine glands, including primary pigmented nodular adrenocortical disease (some with Cushing's syndrome), pituitary adenoma, testicular neoplasms, thyroid adenoma or carcinoma, and ovarian cysts. Additional unusual manifestations include psammomatous melanotic schwannoma, breast ductal adenoma, and a rare bone tumor, osteochondromyxoma. Carcinoid syndrome is the term applied to a constellation of symptoms mediated by various humoral factors elaborated by some carcinoid tumors; the major manifestations are diarrhea, flushing, bronchospasm, and cardiac valvular lesions. Mast cell diseases include all disorders of mast cell proliferation. These diseases can be limited to the skin, referred to as "cutaneous mastocytosis," or involve extracutaneous tissues, called "systemic mastocytosis." Patients present with urticaria pigmentosa, mastocytoma, or diffuse cutaneous mastocytosis. Systemic involvement may be gastronintestinal, hematologic, neurologic, and skeletal.

Adrenal pathophysiology: lessons from the Carney complex.

The Carney complex (CNC) is a dominantly inherited syndrome responsible mainly for spotty skin pigmentation (lentiginosis), endocrine overactivity, and cardiac myxomas. Adrenocorticotropic hormone independent Cushing's syndrome due to primary pigmented nodular adrenocortical disease (PPNAD) is a main characteristic of CNC. PPNAD is a very rare cause of Cushing's syndrome due to a primary bilateral adrenal defect that can be also observed in some patients without other CNC manifestations nor familial history. One of the putative CNC genes, located on 17q22-24, has been identified as the regulatory subunit R1A of protein kinase A (PRKAR1A). Heterozygous inactivating mutations of PRKAR1A have been reported initially in about 45% of the CNC index cases and could be found in about 80% of the CNC families presenting mainly with Cushing's syndrome. PRKAR1A is a key component of the cyclic AMP signaling pathway that has been implicated in endocrine tumorigenesis and could, at least partly, function as a tumor suppressor gene. Interestingly, patients with isolated PPNAD and no familial history of CNC can also present a germline de novo mutation of PRKAR1A. Somatic mutations of PRKAR1A have been found in PPNAD as a mechanism of inactivation of the wild-type allele, in a patient already presenting a germline mutation, and in a subset of sporadic secreting adrenocortical adenomas with clinical, hormonal, and pathological features quite similar to PPNAD. This review will summarize the recent findings on CNC from the perspective of the pathophysiology of adrenal Cushing's syndrome and PPNAD.

Multiple endocrine neoplasia--introduction.

Each multiple endocrine neoplasia (MEN) syndrome expresses striking features of hormone oversecretion from its own characteristic group of tissues. Additional expressions include non-hormonal tumours in each MEN syndrome and selected cancers in some syndromes. The complexity of its stereotyped features results in difficult management issues that often justify cooperation across multiple specialties. MEN syndromes, though rare, have long received intense study as models for more common diseases. The syndromal nature often with a large pedigree has promoted recent discovery of the main gene that differs for each of the six MEN syndromes. Each mutant gene has been introduced into clinical decision-making and into further clarification of tumorigenesis. This mini-symposium is related to the 9th International Workshop on Multiple Endocrine Neoplasia in June 2004; it consists of six manuscripts. They report new developments in clinical practices and in basic understandings about this rapidly advancing field.

Molecular pathology of the MEN1 gene.

Multiple endocrine neoplasia type 1 (MEN1), among all syndromes, causes tumors in the highest number of tissue types. Most of the tumors are hormone producing (e.g., parathyroid, enteropancreatic endocrine, anterior pituitary) but some are not (e.g., angiofibroma). MEN1 tumors are multiple for organ type, for regions of a discontinuous organ, and for subregions of a continuous organ. Cancer contributes to late mortality; there is no effective prevention or cure for MEN1 cancers. Morbidities are more frequent from benign than malignant tumor, and both are indicators for screening. Onset age is usually earlier in a tumor type of MEN1 than of nonhereditary cases. Broad trends contrast with those in nonneoplastic excess of hormones (e.g., persistent hyperinsulinemic hypoglycemia of infancy). Most germline or somatic mutations in the MEN1 gene predict truncation or absence of encoded menin. Similarly, 11q13 loss of heterozygosity in tumors predicts inactivation of the other MEN1 copy. MEN1 somatic mutation is prevalent in nonhereditary, MEN1-like tumor types. Compiled germline and somatic mutations show almost no genotype/phenotype relation. Normal menin is 67 kDa, widespread, and mainly nuclear. It may partner with junD, NF-kB, PEM, SMAD3, RPA2, FANCD2, NM23beta, nonmuscle myosin heavy chain II-A, GFAP, and/or vimentin. These partners have not clarified menin's pathways in normal or tumor tissues. Animal models have opened approaches to menin pathways. Local overexpression of menin in Drosophila reveals its interaction with the jun-kinase pathway. The Men1+/- mouse has robust MEN1; its most important difference from human MEN1 is marked hyperplasia of pancreatic islets, a tumor precursor stage.

Tumores endocrinos pancreáticos / Endocrine tumors of the pancreas

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Clinical features and anesthetic management of multiple endocrine neoplasia associated with pheochromocytoma.

OBJECTIVE: To investigate clinical features and anesthetic management of multiple endocrine neoplasia (MEN) associated with pheochromocytoma. METHODS: Medical records of patients who were diagnosed as multiple endocrine neoplasia associated with pheochromocytoma in our hospital from April 1977 to April 2001 were reviewed retrospectively. The demographic data, clinical presentations, family history, biochemical examinations, type of MEN, sequence of different surgical procedures, anesthetic methods and hemodynamics during surgery were analyzed. RESULTS: Thirteen cases of MEN associated with pheochromocytoma were investigated, accounting for 6% (13/213) of the pheochromocytoma patients admitted into our hospital. Nine of the 13 patients presented as type IIa MEN (Sipple syndrome), one as type IIb MEN, and three as mixed MEN. Four patients with type IIa MEN had a family history of similar disease. Five patients with other coexisting endocrine disorders first underwent excision of the pheochromocytomas, although only two had hypertensive symptoms at the time of admittance. Seven patients without histories of hypertension received surgical treatment for pheochromocytoma secondly. The excision of pheochromocytoma was performed under general anesthesia in 8 patients and epidural block in 4 patients. Marked hemodynamic fluctuation was recorded in 8 patients. No perioperative death was recorded. CONCLUSION: Pheochromocytoma may be linked to other endocrine disorders during MEN, either as the main clinical presentation or most frequently as an occult tumor. Recognition of this feature of pheochromocytoma is of importance to the improvement of diagnosis and treatment both for pheochromocytoma and MEN.

[New perspectives in diagnosis and therapy of endocrine gastroenteropancreatic (GEP) tumors with somatostatin analogues]. / Nuove prospettive nella diagnosi e terapia dei tumori endocrini gastroenteropancreatici (GEP) con analoghi della somatostatina.

In the last decade important progresses have been obtained in the diagnosis and therapy of endocrine gastroenteropancreatic (GEP) tumors, mainly derived from the somatostatin receptors characterization and the introduction of long acting somatostatin analogues. Receptorial scintigraphy with radio-labeled analogues (Octreoscan) is the first choice investigation for staging and follow-up of endocrine GEP tumors, thanks to the high sensitivity in revealing the primary tumor and metastases, and for its capability to reveal lesions that are not identified by other imaging methods. Moreover, somatostatin analogues uptake by tumors allow us to use radiopharmaceutical compounds for advanced disease treatment. Between the radio-labeled drugs until now studied, interesting results have been obtained by DOTA-lanreotide (MAURITIUS), DOTA0 Tyr3-octreotide (DOTATOC) and DOTA0 Tyr3-octreotate, bound to beta-emitting radio-isotope suitable for therapeutic use. In the field of the pharmacological therapy of GEP tumors, the clinical trials show that somatostatin analogues reduce the symptoms related to functionally active tumors and stabilize or slow tumor growth improving the patient quality of life. Although somatostatin analogues alone could not be able to cure GEP tumors, their early utilization in association with surgical debulking of primary tumor and metastases, embolization or chemoembolization, and interferon, chemotherapy and radio-metabolic therapy (mainly directed to the destruction of micrometastases), increases the possibility of a radical therapeutic intervention. The continuous evolution of pharmacological research provides always new analogues (octreotide LAR, lanreotide, vapreotide, BIM-23244, BN 81644, PTR-3173, BIM-23A387, SOM-230, etc.) with different pharmacokinetic and receptorial properties and acting with more effectiveness in the different individual clinical situations. In this context there have been recently introduced also the "chimeric" analogues. On the other hand, the widespread utilization of molecular biology and immunohistochemical methods can allow, in perspective, to better define the receptorial pattern of individual endocrine tumors, after their surgical removal. The necessity to integrate endocrinological, nuclear medicine, surgical, oncologic and laboratory competencies behaves a multidisciplinary approach based on the utilization of diagnostic-therapeutic protocols supplying comparable results. It does not appear unjustified to expect, in the future, a scenery of more "individual" and more effective therapies for patients affected by GEP tumours.

Mutations of the gene encoding the protein kinase A type I-alpha regulatory subunit (PRKAR1A) in patients with the "complex of spotty skin pigmentation, myxomas, endocrine overactivity, and schwannomas" (Carney complex).

Carney complex (CNC) is a familial multiple neoplasia syndrome associated with abnormal skin and mucosal pigmentation. The complex has features overlapping those of McCune-Albright syndrome (MAS) and the other multiple endocrine neoplasias (MENs). CNC is inherited as an autosomal dominant trait, and the responsible genes have been mapped by linkage analysis to loci at 2p16 and 17q22-24. Because of its unusual biochemical features (e.g., paradoxical responses to various endocrine signals) and its clinical similarities to MAS, genes implicated in cyclic nucleotide-dependent signaling, including GNAS1 (which is responsible for MAS), had been considered likely candidates for causing CNC. The gene encoding the protein kinase A (PKA) type I-alpha regulatory subunit (RI alpha), PRKAR1A, had been mapped to 17q22-24; loss-of-heterozygosity (LOH) analysis using polymorphic markers from this region revealed consistent changes in tumors from patients with CNC, including those from one family previously mapped to 17q22-24. Investigation of a polymorphic site within the 5' of the PRKAR1A gene showed segregation with the disease and retention of the allele bearing the disease gene in CNC tumors. Mutations of the PRKAR1A gene were also found to have occurred de novo in sporadic cases of CNC; no mutations were found in kindreds mapping to 2p16. Thus, genetic heterogeneity in CNC was confirmed; in total, 41% of all patients with CNC had mutations in the PRKAR1A gene. All mutations were frameshifts, insertions, and deletions that led to nonsense mRNA and premature termination of the predicted peptide product. Functional studies in CNC tumors suggested that inactivating mutations of the PRKAR1A gene led to nonsense mRNA decay (the mutant peptide product was not present) and were associated with dysregulated PKA activity, increased responsiveness to cAMP, and excess of type-II PKA activity. We conclude that the PRKAR1A gene, coding for the RIalpha subunit of PKA, a critical cellular component of a number of cyclic nucleotide-dependent signaling pathways, is mutated in a subset of patients with CNC. In their tumors, there is LOH of the normal allele, suggesting that normal RI-alpha may have tumor suppression function in the tissues affected by CNC. An excess of type-II PKA activity was present in affected tissues, which may be responsible for the apparent tumorigenicity of PRKAR1A mutations in endocrine tissues.

[The GDNF family: from neurotrophic factors to oncogenesis]. / Semeistvo GDNF: ot neirotrofnykh faktorov k onkogenezu.

The structure and in vivo functions of the glial cell-derived neurotrophic factor (GDNF) family ligands (GFLs) and their high-affinity receptors are considered. These proteins play an important role in the development of the nervous system, morphogenesis of the kidneys, and in regulation of spermatogenesis. Tyrosine kinase Ret is a receptor component common for all GFLs. Its role in multiple endocrine neoplasia type 2 (MEN2) is discussed.