title: Reduced transcription of TCOF1 in adult cells of Treacher Collins syndrome patients.
abstract: BACKGROUND
  Treacher Collins syndrome (TCS) is an autosomal dominant craniofacial disorder caused by frameshift deletions or duplications in the TCOF1 gene. These mutations cause premature termination codons, which are predicted to lead to mRNA degradation by nonsense mediated mRNA decay (NMD). Haploinsufficiency of the gene product (treacle) during embryonic development is the proposed molecular mechanism underlying TCS. However, it is still unknown if TCOF1 expression levels are decreased in post-embryonic human cells.
  
  
  METHODS
  We have estimated TCOF1 transcript levels through real time PCR in mRNA obtained from leucocytes and mesenchymal cells of TCS patients (n = 23) and controls (n = 18). Mutational screening and analysis of NMD were performed by direct sequencing of gDNA and cDNA, respectively.
  
  
  RESULTS
  All the 23 patients had typical clinical features of the syndrome and pathogenic mutations were detected in 19 of them. We demonstrated that the expression level of TCOF1 is 18-31% lower in patients than in controls (p < 0.05), even if we exclude the patients in whom we did not detect the pathogenic mutation. We also observed that the mutant allele is usually less abundant than the wild type one in mesenchymal cells.
  
  
  CONCLUSIONS
  This is the first study to report decreased expression levels of TCOF1 in TCS adult human cells, but it is still unknown if this finding is associated to any phenotype in adulthood. In addition, as we demonstrated that alleles harboring the pathogenic mutations have lower expression, we herein corroborate the current hypothesis of NMD of the mutant transcript as the explanation for diminished levels of TCOF1 expression. Further, considering that TCOF1 deficiency in adult cells could be associated to pathologic clinical findings, it will be important to verify if TCS patients have an impairment in adult stem cell properties, as this can reduce the efficiency of plastic surgery results during rehabilitation of these patients.
authors.affiliation: Centro de Estudos do Genoma Humano, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil. cmasotti@ib.usp.br
authors.forename: Cibele
authors.initials: C
authors.lastname: Masotti
authors.forename: Camila C
authors.initials: CC
authors.lastname: Ornelas
authors.forename: Alessandra
authors.initials: A
authors.lastname: Splendore-Gordonos
authors.forename: Ricardo
authors.initials: R
authors.lastname: Moura
authors.forename: Têmis M
authors.initials: TM
authors.lastname: Félix
authors.forename: Nivaldo
authors.initials: N
authors.lastname: Alonso
authors.forename: Anamaria A
authors.initials: AA
authors.lastname: Camargo
authors.forename: Maria Rita
authors.initials: MR
authors.lastname: Passos-Bueno
mesh_terms: D000293:Adolescent; D000328:Adult; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007962:Leukocytes / Q000378:metabolism; D008297:Male; D008342:Mandibulofacial Dysostosis / Q000235:genetics* / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000378:metabolism; D008875:Middle Aged; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics*; D010750:Phosphoproteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D055815:Young Adult
chemical_list: D009687:Nuclear Proteins; D010750:Phosphoproteins; C105442:TCOF1 protein, human