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General Information
Name
LEOPARD syndrome 2
FlyBase ID
FBhh0000132
Disease Ontology Term
Parent Disease
Overview

This report describes LEOPARD syndrome 2 (LPRD2), which is a subtype of LEOPARD syndrome; LPRD2 exhibits autosomal dominant inheritance. The human gene implicated in this disease is RAF1, which encodes Raf-1 proto-oncogene, serine/threonine kinase, a kinase that acts within the RAS-RAF-MEK-ERK pathway. RAF1 is also associated with the diseases Noonan syndrome 5 (OMIM:611553, FBhh0000131) and dilated cardiomyopathy-1NN (OMIM:615916, FBhh0000156). See, in addition, FBhh0000558, a fly model of RAS-RAF-MEK-ERK-pathway-related cancer using RAF1. There is one high-scoring fly ortholog, Raf, for which RNAi targeting constructs, alleles caused by insertional mutagenesis, and classical amorphic alleles have been generated. Dmel\Raf is orthologous to two additional human genes, ARAF and BRAF.

Multiple transgenic constructs of the human Hsap\RAF1 gene have been introduced into flies, including wild-type RAF1, gain-of-function RAF1, UAS and heat-shock promoter constructs, and genes carrying an N-terminal deletion. Cardiomyopathy, which is frequently observed in LPRD2 patients, has been investigated using the fly model with Hsap\RAF1 (FBhh0000156).

Animals homozygous for amorphic mutations of Dmel\Raf exhibit lethality in the late larval stage; imaginal discs are undeveloped. Embryos lacking all Dmel\Raf activity (derived from homozygous null germline clones in the mother and not rescued by paternal contribution) die in early embryogenesis. Cardiomyopathy has also been investigated using the fly Raf gene (FBhh0000156). Many physical and genetic interactions have been described for Dmel\Raf; see below and in the gene report for Raf.

[updated Jun. 2017 by FlyBase; FBrf0222196]

Disease Summary Information
Parent Disease Summary: LEOPARD syndrome
Symptoms and phenotype

LEOPARD is an acronym for the manifestations of this syndrome as listed by Gorlin et al. (1969, pubmed:5771505): multiple lentigines (small pigmented skin spots), electrocardiographic conduction abnormalities, ocular hypertelorism, pulmonic stenosis, abnormal genitalia, retardation of growth, and sensorineural deafness. [from OMIM:151100, 2015.04.10]

Specific Disease Summary: LEOPARD syndrome 2
OMIM report

[LEOPARD SYNDROME 2; LPRD2](https://omim.org/entry/611554)

Human gene(s) implicated

[RAF1 PROTOONCOGENE, SERINE/THREONINE KINASE ; RAF1](https://omim.org/entry/164760)

Symptoms and phenotype

Of 17 Noonan syndrome patients with a RAF1 mutation in either of two hotspots (clustering around ser259 or ser612), 16 (94%) had hypertrophic cardiomyopathy (CMH; see OMIM:192600), compared with an 18% prevalence of CMH among Noonan syndrome patients in general (Pandit et al., 2007, pubmed:17603483). Pandit et al. (2007) also scanned RAF1 exons mutated in Noonan and LEOPARD syndrome patients in 241 unrelated individuals with nonsyndromic CMH who did not have mutations in 8 myofilament genes known to cause CMH, and the authors identified a thr260-to-ile mutation in the RAF1 gene in one patient (Pandit et al., 2007, pubmed:17603483). [from OMIM:164760, 2016.01.19]

A large percentage (70%-90%) of persons with Noonan syndrome and a RAF1 pathogenic variant have hypertrophic cardiomyopathy (HCM), which is significantly higher than the 20% with HCM observed in the general NS population. Moreover, this genotype-phenotype correlation seems to be domain-specific, as HCM appears to be associated with pathogenic variants affecting the region encoding the N-terminal 14-3-3 consensus site or the C-terminus. [from GeneReviews, Noonan Syndrome with Multiple Lentigines, pubmed:20301557 2016.01.20]

Genetics

LEOPARD syndrome 2 is caused by mutation in the RAF1 gene. Noonan syndrome 5 (NS5) (OMIM:611553) is also caused by mutation in RAF1, indicating that the 2 disorders are allelic. [From OMIM:611553, 2016.01.15]

Cellular phenotype and pathology
Molecular information

RAF1 is a serine-threonine kinase that activates MEK1 (OMIM:176872) and MEK2 (OMIM:601263). Ectopically expressed RAF1 mutants from the two hypertrophic cardiomyopathy (CMH; see OMIM:192600) hotspots (around ser259 or ser612) linked to LEOPARD syndrome 2 and/or Noonan syndrome 5 had increased kinase activity and enhanced ERK (see 176948) activation, whereas non-CMH-associated mutants were kinase impaired. (Pandit et al., 2007, pubmed:17603483). Mutations in the CR2 domain, but not the CR3 domain, of RAF1 are associated with hypertrophic cardiomyopathy (Razzaque et al., 2007, pubmed:17603482). [From OMIM:611553 and OMIM:164760, 2016.01.19]

RAF1 is ubiquitously expressed and encodes a protein of 648 amino acids with three conserved regions (CR). CR1 contains a Ras-binding domain; CR2 is a site of regulatory phosphorylation and association with the 14-3-3 protein. CR1 and CR2 both have negative regulatory function, removal of which results in oncogenic activity. The kinase domain, CR3, also associates with 14-3-3. The protein is highly regulated with numerous serine and threonine residues that can be phosphorylated, resulting in activation or inactivation. The serine at residue 259, which is in CR2, is particularly important. In the inactive state, the N-terminus of RAF1 interacts with and inactivates the kinase domain at the C-terminus. This conformation is stabilized by 14-3-3 protein dimers that bind to phosphorylated Ser259 and Ser261. Dephosphorylation of Ser259 facilitates binding of RAF1 to RAS-GTP and propagation of the signal through the RAS-MAPK cascade via RAF1 MEK kinase activity. [from GeneReviews, Noonan Syndrome with Multiple Lentigines, pubmed:20301557 2016.01.20]

External links
Disease synonyms
LPRD2
LEOPARD syndrome 2; LPRD2
Ortholog Information
Human gene(s) in FlyBase
    Human gene (HGNC)
    D. melanogaster ortholog (based on DIOPT)
    Comments on ortholog(s)

    Many to one: 3 human to 1 Drosophila.

    Other mammalian ortholog(s) used
      D. melanogaster Gene Information (1)
      Gene Snapshot
      Raf oncogene (Raf) encodes a serine-threonine protein kinase that acts downstream of the product of ras. It activates the MEK/ERK pathway to regulate cell proliferation, differentiation and survival downstream of receptor tyrosine kinases such as those encoded by tor, Egfr, and sev. [Date last reviewed: 2019-03-14]
      Cellular component (GO)
      Gene Groups / Pathways
      Comments on ortholog(s)

      Ortholog of human BRAF, ARAF, and RAF1 (1 Drosophila to 3 human).

      Dmel\Raf shares 43% identity and 54% similarity with human BRAF, 44% identity and 58% similarity with human ARAF, and 47% identity and 60% similarity with human RAF1.

      Orthologs and Alignments from DRSC
      DIOPT - DRSC Integrative Ortholog Prediction Tool - Click the link below to search for orthologs in Humans
      Synthetic Gene(s) Used (0)
      Summary of Physical Interactions (89 groups)
      protein-protein
      Interacting group
      Assay
      References
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting, anti tag western blot
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      enzymatic study, autoradiography
      anti tag coimmunoprecipitation, peptide massfingerprinting, western blot, two hybrid
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      two hybrid, anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting, anti tag western blot
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, anti tag western blot
      anti tag coimmunoprecipitation, peptide massfingerprinting, anti tag western blot
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, anti tag western blot
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, anti tag western blot
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, anti tag western blot, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, anti tag western blot, two hybrid
      anti tag coimmunoprecipitation, anti tag western blot, two hybrid, pull down
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, anti tag western blot
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, anti tag western blot
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      anti tag coimmunoprecipitation, peptide massfingerprinting
      Alleles Reported to Model Human Disease (Disease Ontology) (5 alleles)
      Models Based on Experimental Evidence ( 3 )
      Modifiers Based on Experimental Evidence ( 3 )
      Genetic Tools, Stocks and Reagents
      Sources of Stocks
      Contact lab of origin for a reagent not available from a public stock center.
      Bloomington Stock Center Disease Page
      Selected mammalian transgenes
      Allele
      Transgene
      Publicly Available Stocks
      Selected Drosophila transgenes
      Allele
      Transgene
      Publicly Available Stocks
      RNAi constructs available
      Allele
      Transgene
      Publicly Available Stocks
      Selected Drosophila classical alleles
      Allele
      Allele class
      Mutagen
      Publicly Available Stocks
      amorphic allele - genetic evidence
      nitrosomethyl urea
      loss of function allele
      amorphic allele - genetic evidence
      X ray
      amorphic allele - genetic evidence
      1,2-dichloroethane
      amorphic allele - genetic evidence
      spontaneous
      amorphic allele - genetic evidence
      ethyl methanesulfonate
      loss of function allele
      ethyl methanesulfonate
      hycanthon methanesulfonate
      amorphic allele - genetic evidence
      ethyl methanesulfonate
      amorphic allele - genetic evidence
      ethyl methanesulfonate
      amorphic allele - genetic evidence
      X ray
      amorphic allele - genetic evidence
      ethyl methanesulfonate
      References (6)