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

Noonan syndrome (MIM 163950) is an autosomal dominant disorder characterized by dysmorphic facial features, proportionate short stature and heart disease (most commonly pulmonic stenosis and hypertrophic cardiomyopathy). Webbed neck, chest deformity, cryptorchidism, mental retardation and bleeding diatheses also are frequently associated with this disease. This syndrome is relatively common, with an estimated incidence of 1 in 1,000-2,500 live births. It has been mapped to a 5-cM region (NS1) [corrected] on chromosome 12q24.1, and genetic heterogeneity has also been documented. Here we show that missense mutations in PTPN11 (MIM 176876)-a gene encoding the nonreceptor protein tyrosine phosphatase SHP-2, which contains two Src homology 2 (SH2) domains-cause Noonan syndrome and account for more than 50% of the cases that we examined. All PTPN11 missense mutations cluster in interacting portions of the amino N-SH2 domain and the phosphotyrosine phosphatase domains, which are involved in switching the protein between its inactive and active conformations. An energetics-based structural analysis of two N-SH2 mutants indicates that in these mutants there may be a significant shift of the equilibrium favoring the active conformation. This implies that they are gain-of-function changes and that the pathogenesis of Noonan syndrome arises from excessive SHP-2 activity.
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PMID:Mutations in PTPN11, encoding the protein tyrosine phosphatase SHP-2, cause Noonan syndrome. 1170 59

Cardiofaciocutaneous (CFC) syndrome is a multiple congenital anomalies/mental retardation syndrome characterized by congenital heart defects, characteristic facial appearance, short stature, ectodermal abnormalities and mental retardation. It was described in 1986, and to date is of unknown genetic etiology. All reported cases are sporadic, born to non-consanguineous parents and have apparently normal chromosomes. Noonan and Costello syndromes remain its main differential diagnosis. The recent finding of PTPN11 missense mutations in 45-50% of the Noonan patients studied with penetrance of almost 100% and the fact that in animals mutations of this gene cause defects of semilunar valvulogenesis, made PTPN11 mutation screening in CFC patients a matter of interest. We sequenced the entire coding region of the PTPN11 gene in ten well-characterised CFC patients and found no base changes. We also studied PTPN11 cDNA in our patients and demonstrated that there are no interstitial deletions either. The genetic cause of CFC syndrome remains unknown, and PTPN11 can be reasonably excluded as a candidate gene for the CFC syndrome, which we regard as molecular evidence that CFC and Noonan syndromes are distinct genetic entities.
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PMID:PTPN11 mutations are not responsible for the Cardiofaciocutaneous (CFC) syndrome. 1252 7

Noonan syndrome (NS) is an autosomal dominant disorder comprising short stature, facial dysmorphism, short and/or webbed neck, heart defects, and cryptorchidism in males. The gene responsible for the disorder (PTPN11) was recently identified, and explains 30-50% of the cases clinically diagnosed as NS. Cardiofaciocutaneous (CFC) syndrome, a similar but distinct entity, is characterized by relative macrocephaly, characteristic facial appearance, ectodermal abnormalities (sparse and friable hair, sparse eyebrows, hyperkeratotic skin), congenital heart defects, and growth and mental retardation. We describe on a young woman who presents clinical features of NS (short stature, triangular facies, with downslanting palpebral fissures and apparent hypertelorism, webbed neck, pulmonary stenosis, bleeding diathesis, prominent corneal nerves), but with a more prominent ectodermal involvement (sparse and very coarse hair, sparse eyebrows and eyelashes) and developmental delay/mental retardation, which are characteristic of CFC patients. Sequencing of the PTPN11 gene showed a T411M substitution, not previously described in patients with NS. The same mutation was found in her mother and older sister, not initially considered to be affected by NS, but with very subtle clinical findings compatible with this diagnosis. Molecular dynamic studies indicate that this new mutation, similar to other previously described mutations, favors a more active protein conformation. However, the main disruptive effect is not directly in the catalytic domain, suggesting that the location of this mutation could make the protein more susceptible to gene-gene or gene-environment interactions. Atypical cases of NS should be screened for mutations in the PTPN11 gene and in the case of a positive result, first-degree relatives should also be tested for the specific mutation.
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PMID:Clinical variability in a Noonan syndrome family with a new PTPN11 gene mutation. 1538 80

This review summarizes PTPN11 (protein-tyrosine phosphatase, nonreceptor type 11) mutations and genotype-phenotype correlations in Noonan syndrome (NS) and LEOPARD syndrome (LS). PTPN11 mutations have been identified in approximately 40% of NS patients and in >80% of LS patients. Since the vast majority of mutations reside in and around the broad intramolecular interaction surface between the N-SH2 and PTP domains of the PTPN11 protein, they have been suggested to affect the intramolecular N-SH2/PTP binding in the absence of a phosphopeptide, leading to excessive phosphatase activities. The type of mutations is diverse in NS and limited in LS, and is almost mutually exclusive between NS and LS. Clinical assessment in NS patients implies that cardiovascular anomalies and hematologic abnormalities are predominant in mutation positive patients, hypertrophic cardiomyopathy is predominant in mutation negative patients, and growth deficiency, mental retardation, and minor somatic anomalies are similar between the two groups of patients. Phenotypic evaluation in LS patients suggests that a hypertrophic cardiomyopathy rather than an electrocardiographic conduction abnormality is characteristic of PTPN11 mutation positive patients.
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PMID:PTPN11 mutations and genotype-phenotype correlations in Noonan and LEOPARD syndromes. 1620 80

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.
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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.
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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.
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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.
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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.
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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).
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PMID:The RAS/MAPK syndromes: novel roles of the RAS pathway in human genetic disorders. 1847 Sep 43


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