Variability of systemic and oro-dental phenotype in two families with non-lethal Raine syndrome with FAM20C mutations

Background: Raine syndrome (RS) is a rare autosomal recessive bone dysplasia typified by osteosclerosis and dysmorphic facies due to FAM20C mutations. Initially reported as lethal in infancy, survival is possible into adulthood. We describe the molecular analysis and clinical phenotypes of five individuals from two consanguineous Brazilian families with attenuated Raine Syndrome with previously unreported features. Methods: The medical and dental clinical records were reviewed. Extracted deciduous and permanent teeth as well as oral soft tissues were analysed. Whole exome sequencing was undertaken and FAM20C cDNA sequenced in family 1. Results: Family 1 included 3 siblings with hypoplastic Amelogenesis Imperfecta (AI) (inherited abnormal dental enamel formation). Mild facial dysmorphism was noted in the absence of other obvious skeletal or growth abnormalities. A mild hypophosphataemia and soft tissue ectopic mineralization were present. A homozygous FAM20C donor splice site mutation (c.784 + 5 g > c) was identified which led to abnormal cDNA sequence. Family 2 included 2 siblings with hypoplastic AI and tooth dentine abnormalities as part of a more obvious syndrome with facial dysmorphism. There was hypophosphataemia, soft tissue ectopic mineralization, but no osteosclerosis. A homozygous missense mutation in FAM20C (c.1487C > T; p.P496L) was identified. Conclusions: The clinical phenotype of non-lethal Raine Syndrome is more variable, including between affected siblings, than previously described and an adverse impact on bone growth and health may not be a prominent feature. By contrast, a profound failure of dental enamel formation leading to a distinctive hypoplastic AI in all teeth should alert clinicians to the possibility of FAM20C mutations

Manifestações bucais de pacientes com doenças renais hereditárias e nefrocalcinose e análise de variação de seqüência de pacientes com amelogênese imperpeita e FHHNC

Tese (doutorado)—Universidade de Brasília, Programa de Pós-Graduação em Ciências da Saúde, 2012.O objetivo desse trabalho foi relatar as manifestações bucais de pacientes com doenças renais hereditárias e nefrocalcinose atendidos no serviço de nefrologia de três Hospitais da área metropolitana de Brasília, e realizar análise de mutação abordando genes candidatos em três pacientes que apresentaram fenótipo de amelogênese imperfeita (AI). Um total de seis pacientes com hipomagnesemia e hipercalciúria familiar com nefrocalcinose (FHHNC), um paciente com acidose tubular renal distal (ATRd), dois pacientes com ATRd e surdez, e uma paciente com osteopetrose foram estudados. Todos os pacientes apresentaram defeitos de desenvolvimento do esmalte variando de leves opacidades difusas a hipoplasias severas. Com exceção da paciente com osteopetrose que apresentou maloclusão e alteração da cronologia de erupção dentária com retenção de dentes decíduos e permanentes, não foram observadas outras manifestações bucais nos pacientes. Em dois dos três pacientes com FHHNC e AI que foram submetidos à análise de variação de sequência, foram observadas três substituições em heterozigose composta nos genes CLDN16 e CLDN19. O paciente com fenótipo de AI hipomaturada e hipoplásica apresentou as substituições F85L na CLDN16 e G20D e L90R na CLDN19. O paciente com AI hipoplásica apresentou as substituições F85L na CLDN16 e G20D e R200Q na CLDN19. Aparentemente, a outra paciente apresentou uma deleção no gene CLDN16 que precisa ser confirmada por outros métodos. Os resultados sugerem que pacientes com doenças renais hereditárias e nefrocalcinose podem apresentar defeitos de desenvolvimento do esmalte com fenótipo de AI e que pacientes com AI sem etiologia definida podem ser portadores de doenças renais hereditárias. Outros estudos são necessários para comprovar o efeito funcional da associação das substituições de aminoácido encontrada nos pacientes com AI e FHHNC desse estudo. ______________________________________________________________________________ ABSTRACTThe aim of this study was to describe the oral manifestations of inherited renal diseases patients with nephrocalcinosis followed by three Nephrology Services from three Hospitals located in the metropolitan area of Brasilia. Besides, three patients who exhibited enamel defects resembling amelogenesis imperfecta (AI) were submitted to sequence analysis using candidate genes approach. A total of six patients with hypomagnesemia and hypercalciuria with nephrocalcinosis (FHHNC), one patient with distal renal tubular acidosis (dRTA), two patients with dRTA and hearing loss, and one patient with osteopetrosis were included in this study. All patients exhibited developmental defects of enamel ranging from slight diffuse opacities to severe hypoplasia. Except for the osteopetrosis patient who also exhibited malloclusion, altered tooth eruption chronology and deciduous and permanent teeth retention, patients did not present any other oral manifestation. Two of the patients with FHHNC and enamel defects resembling AI who were submitted to sequence analysis, presented three compound heterozygous substitutions in the CLDN16 and CLDN19 genes. The patient with hypomature and hypoplasic AI phenotype presented a F85L substitution in the CLDN16 and a G20D and a L90R substitution in the CLDN19. The patient with hypoplasic AI presented a F85L substitution in the CLDN16 and a G20D and a R200Q substitution in the CLDN19. One patient exhibited an apparent deletion in the CLDN16 gene which has to be confirmed using other methods. The results suggest that inherited renal diseases patients with nephrocalcinosis may present developmental defects of enamel resembling AI, and that non-diagnosed AI patients` may present inherited renal disturbances. Other studies are necessary to determine the functional effects of the amino acids substitutions detected in this study in the FHHNC patients with AI

Gingival proteomics reveals the role of TGF beta and YAP/TAZ signaling in Raine syndrome fibrosis

International audienceRaine syndrome (RNS) is a rare autosomal recessive osteosclerotic dysplasia. RNS is caused by loss-of-function disease-causative variants of the FAM20C gene that encodes a kinase that phosphorylates most of the secreted proteins found in the body fluids and extracellular matrix. The most common RNS clinical features are generalized osteosclerosis, facial dysmorphism, intracerebral calcifications and respiratory defects. In non-lethal RNS forms, oral traits include a well-studied hypoplastic amelogenesis imperfecta (AI) and a much less characterized gingival phenotype. We used immunomorphological, biochemical, and siRNA approaches to analyze gingival tissues and primary cultures of gingival fibroblasts of two unrelated, previously reported RNS patients. We showed that fibrosis, pathological gingival calcifications and increased expression of various profibrotic and pro-osteogenic proteins such as POSTN, SPARC and VIM were common findings. Proteomic analysis of differentially expressed proteins demonstrated that proteins involved in extracellular matrix (ECM) regulation and related to the TGFbeta/SMAD signaling pathway were increased. Functional analyses confirmed the upregulation of TGF beta/SMAD signaling and subsequently uncovered the involvement of two closely related transcription cofactors important in fibrogenesis, Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ). Knocking down of FAM20C confirmed the TGFbeta-YAP/TAZ interplay indicating that a profibrotic loop enabled gingival fibrosis in RNS patients. In summary, our in vivo and in vitro data provide a detailed description of the RNS gingival phenotype. They show that gingival fibrosis and calcifications are associated with, and most likely caused by excessed ECM production and disorganization. They furthermore uncover the contribution of increased TGFbeta−YAP/TAZ signaling in the pathogenesis of the gingival fibrosis