@article {38, title = {Cutaneous skeletal hypophosphatemia syndrome (CSHS) is a multilineage somatic mosaic RASopathy.}, journal = {J Am Acad Dermatol}, volume = {75}, year = {2016}, month = {2016 Aug}, pages = {420-7}, abstract = {

BACKGROUND: We recently demonstrated multilineage somatic mosaicism in cutaneous skeletal hypophosphatemia syndrome (CSHS), which features epidermal or melanocytic nevi, elevated fibroblast growth factor (FGF)-23, and hypophosphatemia, finding identical RAS mutations in affected skin and bone.

OBJECTIVE: We sought to: (1) provide an updated overview of CSHS; (2) review its pathobiology; (3)~present a new patient with CSHS; and (4) discuss treatment modalities.

METHODS: We searched PubMed for "nevus AND rickets," and "nevus AND hypophosphatemia," identifying cases of nevi with hypophosphatemic rickets or elevated serum FGF-23. For our additional patient with CSHS, we performed histopathologic and radiographic surveys of skin and skeletal lesions, respectively. Sequencing was performed for HRAS, KRAS, and NRAS to determine causative mutations.

RESULTS: Our new case harbored somatic activating HRAS p.G13~R mutation in affected tissue, consistent with previous findings. Although the mechanism of FGF-23 dysregulation is unknown in CSHS, interaction between FGF and MAPK pathways may provide insight into pathobiology. Anti-FGF-23 antibody KRN-23 may be useful in managing CSHS.

LIMITATIONS: Multilineage RAS mutation in CSHS was recently identified; further studies on mechanism are unavailable.

CONCLUSION: Patients with nevi in association with skeletal disease should be evaluated for serum phosphate and FGF-23. Further studies investigating the role of RAS in FGF-23 regulation are needed.

}, keywords = {Antibodies, Monoclonal, Antibodies, Monoclonal, Humanized, Fibroblast Growth Factor-23, Fibroblast Growth Factors, Genes, ras, Humans, Mosaicism, Nevus, Pigmented, Osteomalacia, Rickets, Hypophosphatemic, Skin Neoplasms, Syndrome}, issn = {1097-6787}, doi = {10.1016/j.jaad.2015.11.012}, author = {Lim, Young H and Ovejero, Diana and Derrick, Kristina M and Collins, Michael T and Choate, Keith A} } @article {114, title = {Dominant de novo DSP mutations cause erythrokeratodermia-cardiomyopathy syndrome.}, journal = {Hum Mol Genet}, volume = {25}, year = {2016}, month = {2016 Jan 15}, pages = {348-57}, abstract = {

Disorders of keratinization (DOK) show marked genotypic and phenotypic heterogeneity. In most cases, disease is primarily cutaneous, and further clinical evaluation is therefore rarely pursued. We have identified subjects with a novel DOK featuring erythrokeratodermia and initially-asymptomatic, progressive, potentially fatal cardiomyopathy, a finding not previously associated with erythrokeratodermia. We show that de novo missense mutations clustered tightly within a single spectrin repeat of DSP cause this novel cardio-cutaneous disorder, which we term erythrokeratodermia-cardiomyopathy (EKC) syndrome. We demonstrate that DSP mutations in our EKC syndrome subjects affect localization of desmosomal proteins and connexin 43 in the skin, and result in desmosome aggregation, widening of intercellular spaces, and lipid secretory defects. DSP encodes desmoplakin, a primary component of desmosomes, intercellular adhesion junctions most abundant in the epidermis and heart. Though mutations in DSP are known to cause other disorders, our cohort features the unique clinical finding of severe whole-body erythrokeratodermia, with distinct effects on localization of desmosomal proteins and connexin 43. These findings add a severe, previously undescribed syndrome featuring erythrokeratodermia and cardiomyopathy to the spectrum of disease caused by mutation in DSP, and identify a specific region of the protein critical to the pathobiology of EKC syndrome and to DSP function in the heart and skin.

}, keywords = {Amino Acid Sequence, Cardiomyopathies, Child, Child, Preschool, Connexin 43, Desmoplakins, Desmosomes, Female, Humans, Infant, Male, Molecular Sequence Data, Mutation, Missense, Myocardium, Protein Transport, Sequence Alignment, Skin, Skin Diseases, Genetic, Syndrome}, issn = {1460-2083}, doi = {10.1093/hmg/ddv481}, author = {Boyden, Lynn M and Kam, Chen Y and Hern{\'a}ndez-Mart{\'\i}n, Angela and Zhou, Jing and Craiglow, Brittany G and Sidbury, Robert and Mathes, Erin F and Maguiness, Sheilagh M and Crumrine, Debra A and Williams, Mary L and Hu, Ronghua and Lifton, Richard P and Elias, Peter M and Green, Kathleen J and Choate, Keith A} }