Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tuberous sclerosis complex (TSC) is a tumor suppressor gene syndrome with manifestations that can include seizures, mental retardation, autism, and tumors in the brain, retina, kidney, heart, and skin. The products of the TSC1 and TSC2 genes, hamartin and tuberin, respectively, heterodimerize and inhibit the mammalian target of rapamycin (mTOR). We found that tuberin expression increases p42/44 MAPK phosphorylation and B-Raf kinase activity. Short interfering RNA down-regulation of tuberin decreased the p42/44 MAPK phosphorylation and B-Raf activity. Expression of Rheb, the target of the GTPase-activating domain of tuberin, inhibited wild-type B-Raf kinase but not activated forms of B-Raf. The interaction of endogenous Rheb with B-Raf was enhanced by serum and by Ras overexpression. A farnesylation-defective mutant of Rheb co-immunoprecipitated with and inhibited B-Raf but did not activate ribosomal protein S6 kinase, indicating that farnesylation is not required for B-Raf inhibition by Rheb and that B-Raf inhibition and S6 kinase activation are separable activities of Rheb. Consistent with this, inhibition of B-Raf and p42/44 MAPK by Rheb was resistant to rapamycin in contrast to Rheb activation of S6 kinase, which is rapamycin-sensitive. Taken together these data demonstrate that inhibition of B-Raf kinase via Rheb is an mTOR-independent function of tuberin.
 ...
PMID:Regulation of B-Raf kinase activity by tuberin and Rheb is mammalian target of rapamycin (mTOR)-independent. 1515 Feb 71

Tuberous sclerosis complex (TSC) is a tumor suppressor gene syndrome whose manifestations can include seizures, mental retardation, autism, and tumors in the brain, retina, kidney, heart, and skin. The products of the TSC1 and TSC2 genes, hamartin and tuberin, respectively, heterodimerize and inhibit the mammalian target of rapamycin (mTOR). This review focuses on the genetic and biochemical basis of the renal and pulmonary manifestations of TSC, angiomyolipomas, and lymphangiomyomatosis, respectively. Genetic analyses of sporadic angiomyolipomas revealed that all three components (smooth muscle, vessels, and fat) derive from a common progenitor cell, indicating the ability of cells lacking tuberin to differentiate into multiple lineages. Other genetic studies showed that the benign smooth muscle cells of pulmonary lymphangiomyomatosis have the ability to migrate to other organs. These findings suggest that tuberin and hamartin play a role in the regulation of cellular migration and differentiation. We have found that tuberin activates B-Raf kinase and p42/44 MAPK and that cells lacking tuberin have low levels of B-Raf activity. We hypothesize that aberrant B-Raf activity in angiomyolipomas leads to abnormal cellular differentiation and migration.
 ...
PMID:The role of tuberin in cellular differentiation: are B-Raf and MAPK involved? 1638 52

Cardio-facio-cutaneous (CFC) syndrome is characterized by a distinctive facial appearance, heart defects and mental retardation. It phenotypically overlaps with Noonan and Costello syndrome, which are caused by mutations in PTPN11 and HRAS, respectively. In 43 individuals with CFC, we identified two heterozygous KRAS mutations in three individuals and eight BRAF mutations in 16 individuals, suggesting that dysregulation of the RAS-RAF-ERK pathway is a common molecular basis for the three related disorders.
 ...
PMID:Germline KRAS and BRAF mutations in cardio-facio-cutaneous syndrome. 1647 4

The cardiofaciocutaneous (CFC) syndrome is a condition of sporadic occurrence, with patients showing multiple congenital anomalies and mental retardation. It is characterised by failure to thrive, relative macrocephaly, a distinctive face with prominent forehead, bitemporal constriction, absence of eyebrows, hypertelorism, downward-slanting palpebral fissures often with epicanthic folds, depressed nasal root and a bulbous tip of the nose. The cutaneous involvement consists of dry, hyperkeratotic, scaly skin, sparse and curly hair, and cavernous haemangiomata. Most patients have a congenital heart defect, most commonly pulmonic stenosis and hypertrophic cardiomyopathy. The developmental delay usually is moderate to severe. The syndrome is caused by gain-of-function mutations in four different genes BRAF, KRAS, mitogen-activated protein/extracellular signal-regulated kinase MEK1 and MEK2, all belonging to the same RAS-extracellular signal-regulated kinase (ERK) pathway that regulates cell differentiation, proliferation and apoptosis. The CFC syndrome is a member of a family of syndromes that includes the Noonan and Costello syndromes, presenting with phenotypic similarities. Noonan syndrome is caused by mutations in the protein tyrosine phosphatase SHP-2 gene (PTPN11), with a few people having a mutation in KRAS. Costello syndrome is caused by mutations in HRAS. The protein products of these genes also belong to the RAS-ERK pathway. Thus, the clinical overlap of these three conditions, which often poses a problem of differential diagnosis, is explained by their pathogenetic relatedness.
 ...
PMID:The cardiofaciocutaneous syndrome. 1682 33

Cardio-facio-cutaneous (CFC) syndrome is a multiple congenital anomaly/mental retardation syndrome characterized by heart defects, a distinctive facial appearance, ectodermal abnormalities and mental retardation. Clinically, it overlaps with both Noonan syndrome and Costello syndrome, which are caused by mutations in two genes, PTPN11 and HRAS, respectively. Recently, we identified mutations in KRAS and BRAF in 19 of 43 individuals with CFC syndrome, suggesting that dysregulation of the RAS/RAF/MEK/ERK pathway is a molecular basis for CFC syndrome. The purpose of this study was to perform comprehensive mutation analysis in 56 patients with CFC syndrome and to investigate genotype-phenotype correlation. We analyzed KRAS, BRAF, and MAP2K1/2 (MEK1/2) in 13 new CFC patients and identified five BRAF and one MAP2K1 mutations in nine patients. We detected one MAP2K1 mutation in three patients and four new MAP2K2 mutations in four patients out of 24 patients without KRAS or BRAF mutations in the previous study [Niihori et al., 2006]. No mutations were identified in MAPK3/1 (ERK1/2) in 21 patients without any mutations. In total, 35 of 56 (62.5%) patients with CFC syndrome had mutations (3 in KRAS, 24 in BRAF, and 8 in MAP2K1/2). No significant differences in clinical manifestations were found among 3 KRAS-positive patients, 16 BRAF-positive patients, and 6 MAP2K1/2-positive patients. Wrinkled palms and soles, hyperpigmentation and joint hyperextension, which have been commonly reported in Costello syndrome but not in CFC syndrome, were observed in 30-40% of the mutation-positive CFC patients, suggesting a significant clinical overlap between these two syndromes.
 ...
PMID:Molecular and clinical characterization of cardio-facio-cutaneous (CFC) syndrome: overlapping clinical manifestations with Costello syndrome. 1736 77

Cardio-facio-cutaneous (CFC) syndrome is a multiple congenital anomaly/mental retardation syndrome characterized by a distinctive facial appearance, ectodermal abnormalities, and heart defects. Clinically, it overlaps with both Noonan syndrome and Costello syndrome, which are caused by mutations in 2 genes that encode molecules of the RAS/MAPK (mitogen activated protein kinase) pathway (PTPN11 and HRAS, respectively). Recently, mutations in KRAS, BRAF, and MEK1/2 have been identified in patients with CFC syndrome. Somatic mutations in KRAS and BRAF have been identified in various tumors. In contrast, the association with malignancy has not been noticed in CFC syndrome. Here we report a 9-year-old boy diagnosed with CFC syndrome and acute lymphoblastic leukemia. Sequencing analysis of the entire coding region of KRAS and BRAF showed a de novo germline BRAF E501G (1502A-->G) mutation. Molecular diagnosis and careful observations should be considered in children with CFC syndrome because they have germline mutations in proto-oncogenes and might develop malignancy.
 ...
PMID:Leukemia in Cardio-facio-cutaneous (CFC) syndrome: a patient with a germline mutation in BRAF proto-oncogene. 1748 2

The cardiofaciocutaneous (CFC) syndrome is characterized by congenital heart defect, developmental delay, peculiar facial appearance with bitemporal constriction, prominent forehead, downslanting palpebral fissures, curly sparse hair and abnormalities of the skin. CFC syndrome phenotypically overlaps with Noonan and Costello syndromes. Mutations of several genes (PTPN11, HRAS, KRAS, BRAF, MEK1 and MEK2), involved in the mitogen-activated protein kinase (MAPK) pathway, have been identified in CFC-Costello-Noonan patients. Coenzyme Q10 (CoQ10), a lipophilic molecule present in all cell membranes, functions as an electron carrier in the mitochondrial respiratory chain, where it transports electrons from complexes I and II to complex III. CoQ10 deficiency is a rare treatable mitochondrial disorder with various neurological (cerebellar ataxia, myopathy, epilepsy, mental retardation) and extraneurological (cardiomyopathy, nephropathy) signs that are responsive to CoQ10 supplementation. We report the case of a 4-year-old girl who presented a CFC syndrome, confirmed by the presence of a pathogenic R257Q BRAF gene mutation, together with a muscular CoQ10 deficiency. Her psychomotor development was severely impaired, hindered by muscular hypotonia and ataxia, both improving remarkably after CoQ10 treatment. This case suggests that there is a functional connection between the MAPK pathway and the mitochondria. This could be through the phosphorylation of a nuclear receptor essential for CoQ10 biosynthesis. Another hypothesis is that K-Ras, one of the proteins composing the MAPK pathway, might be recruited into the mitochondria to promote apoptosis. This case highlights that CoQ10 might contribute to the pathogenesis of CFC syndrome.
 ...
PMID:Cardiofaciocutaneous (CFC) syndrome associated with muscular coenzyme Q10 deficiency. 1770 71

The RAS proteins and their downstream pathways play pivotal roles in cell proliferation, differentiation, survival and cell death, but their physiological roles in human development had remained unknown. Noonan syndrome, Costello syndrome, and cardio-facio-cutaneous (CFC) syndrome are autosomal dominant multiple congenital anomaly syndromes characterized by a distinctive facial appearance, heart defects, musculocutaneous abnormalities, and mental retardation. A variety of mutations in protein tyrosine phosphatase, non-receptor type 11(PTPN11) has been identified in 50% of Noonan patients. Specific mutations in PTPN11 have been identified in LEOPARD (multiple lentigines, electrocardiographic conduction abnormalities, ocular hypertelorism, pulmonary stenosis, abnormal genitalia, retardation of growth, and sensorineural deafness) syndrome. In 2005, we discovered Harvey-RAS (HRAS) germline mutations in patients with Costello syndrome. This discovery provided a clue to identification of germline mutations in Kirsten-RAS (KRAS), BRAF and mitogen-activated protein kinase kinase 1 and 2 (MAP2K1/MAP2K2) in patients with CFC syndrome. These genes encode molecules in the RAS/RAF/MEK/extracellular signal-regulated kinase (ERK) pathway, leading to a new concept that clinically related disorders, i.e., Noonan, Costello, and CFC syndromes are caused by dysregulation of the RAS/mitogen activated protein kinase (MAPK) pathway. In the present review, we summarize mutations in HRAS, KRAS, BRAF, MAP2K1/2, and PTPN11, the phenotypes of patients with these mutations, the functional properties of mutants and animal models. Finally we suggest that disorders with mutations of molecules in the RAS/MAPK cascade (Noonan, LEOPARD, Costello, and CFC syndromes and neurofibromatosis type I) may be comprehensively termed "the RAS/MAPK syndromes." Details on mutations will be updated in the RAS/MAPK Syndromes Homepage (www.medgen.med.tohoku.ac.jp/RasMapk syndromes.html).
 ...
PMID:The RAS/MAPK syndromes: novel roles of the RAS pathway in human genetic disorders. 1847 Sep 43

Noonan syndrome (NS) and cardio-facio-cutaneous (CFC) syndrome are autosomal dominant disorders characterized by heart defects, facial dysmorphism, ectodermal abnormalities, and mental retardation. There is a significant clinical overlap between NS and CFC syndrome, but ectodermal abnormalities and mental retardation are more frequent in CFC syndrome. Mutations in PTPN11 and KRAS have been identified in patients with NS and those in KRAS, BRAF and MAP2K1/2 have been identified in patients with CFC syndrome, establishing a new role of the RAS/MAPK pathway in human development. Recently, mutations in the son of sevenless gene (SOS1) have also been identified in patients with NS. To clarify the clinical spectrum of patients with SOS1 mutations, we analyzed 24 patients with NS, including 3 patients in a three-generation family, and 30 patients with CFC syndrome without PTPN11, KRAS, HRAS, BRAF, and MAP2K1/2 (MEK1/2) mutations. We identified two SOS1 mutations in four NS patients, including three patients in the above-mentioned three-generation family. In the patients with a CFC phenotype, three mutations, including a novel three amino-acid insertion, were identified in one CFC patient and two patients with both NS and CFC phenotypes. These three patients exhibited ectodermal abnormalities, such as curly hair, sparse eyebrows, and dry skin, and two of them showed mental retardation. Our results suggest that patients with SOS1 mutations range from NS to CFC syndrome.
 ...
PMID:Clinical manifestations in patients with SOS1 mutations range from Noonan syndrome to CFC syndrome. 1865 Oct 97

Mutations in genes coding for transducers participating in the RAS/MAPK pathway have been identified as the molecular cause underlying a group of clinically related developmental disorders with cognitive deficits of variable severity. To determine the spectrum of cognitive defects associated with dysregulation of this signal cascade, we studied the profile of cognitive abilities in patients with mutations affecting the PTPN11, SOS1, HRAS, KRAS, BRAF, RAF1, and MEK1 genes and phenotype-genotype correlations. Our findings support the observation that heterogeneity in cognitive abilities can be at least partially ascribed to the individual affected genes and type of mutation involved. While mutations affecting transducers upstream of RAS were less frequently associated with mental retardation, mutations in downstream components of the pathway were generally associated with a more severe cognitive impairment. Among patients with a heterozygous PTPN11 mutation, the T468M substitution was associated with a mean IQ significantly higher compared to that of individuals carrying the N308D change. Our study provides insights on the range of cognitive abilities in patients with gene mutations causing dysregulation of RAS signaling suggesting that the presence and severity of cognitive involvement can be predicted in part by the gene involved.
 ...
PMID:Cognitive profile of disorders associated with dysregulation of the RAS/MAPK signaling cascade. 1913 93


1 2 3 Next >>