title: Qualitative and quantitative analysis of FBN1 mRNA from 16 patients with Marfan Syndrome.
abstract: BACKGROUND
  Pathogenic mutations in FBN1, encoding the glycoprotein, fibrillin-1, cause Marfan syndrome (MFS) and related connective tissue disorders. In the present study, qualitative and quantitative effects of 16 mutations, identified in FBN1 in MFS patients with systematically described phenotypes, were investigated in vitro.
  
  
  METHODS
  Qualitative analysis was performed with reverse transcription-PCR (RT-PCR) and gel electrophoresis, and quantitative analysis to determine the FBN1 mRNA levels in fibroblasts from the 16 patients with MFS was performed with real-time PCR.
  
  
  RESULTS
  Qualitative analysis documented that the mutations c.4817-2delA and c.A4925G led to aberrant FBN1 mRNA splicing leading to in frame deletion of exon 39 and in exon 39, respectively. No difference in the mean FBN1 mRNA level was observed between the entire group of cases and controls, nor between the group of patients with missense mutations and controls. The mean expression levels associated with premature termination codon (PTC) and splice site mutations were significantly lower than the levels in patients with missense mutations. A high level of FBN1 mRNA in the patient with the missense mutation c.G2447T did not segregate with the mutation in three of his first degree relatives. No association was indicated between the FBN1 transcript level and specific phenotypic manifestations.
  
  
  CONCLUSIONS
  Abnormal FBN1 transcripts were indicated in fibroblasts from patients with the splice site mutation c.4817-2delA and the missense mutation c.A4925G. While the mean FBN1 mRNA expression level in fibroblasts from patients with splice site and PTC mutations were lower than the mean level in patients with missense mutations and controls, inter-individual variability was high. The observation that high level of FBN1 mRNA in the patient with the missense mutation c.G2447T did not segregate with the mutation in the family suggests that variable expression of the normal FBN1 allele may contribute to explain the variability in FBN1 mRNA level.
authors.affiliation: Department of Medical Genetics, Oslo University Hospital, Box 4950, 0424, Oslo, Norway. lena.tjeldhorn@online.no.
authors.forename: Lena
authors.initials: L
authors.lastname: Tjeldhorn
authors.affiliation: Department of Medical Genetics, Oslo University Hospital, Box 4950, 0424, Oslo, Norway. silja.s.amundsen@rr-research.no.|Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway. silja.s.amundsen@rr-research.no.
authors.forename: Silja Svanstrøm
authors.initials: SS
authors.lastname: Amundsen
authors.affiliation: Department of Medical Genetics, Oslo University Hospital, Box 4950, 0424, Oslo, Norway. tuva.baroy@medisin.uio.no.|Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway. tuva.baroy@medisin.uio.no.
authors.forename: Tuva
authors.initials: T
authors.lastname: Barøy
authors.affiliation: TRS National Resource Centre for Rare Disorders, Sunnaas Rehabilitation Hospital, 1450 Nesoddtangen, Norway. svend.rand-hendriksen@medisin.uio.no.|Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway. svend.rand-hendriksen@medisin.uio.no.
authors.forename: Svend
authors.initials: S
authors.lastname: Rand-Hendriksen
authors.affiliation: Department of Cardiothoracic Surgery, Oslo University Hospital, Box 4950, 0424 Oslo, Norway. odd.geiran@medisin.uio.no.|Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway. odd.geiran@medisin.uio.no.
authors.forename: Odd
authors.initials: O
authors.lastname: Geiran
authors.affiliation: Department of Medical Genetics, Oslo University Hospital, Box 4950, 0424, Oslo, Norway. eirik.frengen@medisin.uio.no.|Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway. eirik.frengen@medisin.uio.no.
authors.forename: Eirik
authors.initials: E
authors.lastname: Frengen
authors.affiliation: Department of Medical Genetics, Oslo University Hospital, Box 4950, 0424, Oslo, Norway. benedicte.paus@medisin.uio.no.|Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway. benedicte.paus@medisin.uio.no.
authors.forename: Benedicte
authors.initials: B
authors.lastname: Paus
mesh_terms: D001483:Base Sequence; D002478:Cells, Cultured; D004252:DNA Mutational Analysis; D000071838:Fibrillin-1; D000071837:Fibrillins; D005347:Fibroblasts / Q000378:metabolism*; D020022:Genetic Predisposition to Disease / Q000235:genetics; D005838:Genotype; D006801:Humans; D008382:Marfan Syndrome / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008840:Microfilament Proteins / Q000235:genetics*; D009154:Mutation; D020125:Mutation, Missense; D022821:RNA Splice Sites / Q000235:genetics; D012326:RNA Splicing / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017384:Sequence Deletion; D054392:Adipokines
chemical_list: D000071838:Fibrillin-1; D000071837:Fibrillins; D008840:Microfilament Proteins; D022821:RNA Splice Sites; D012333:RNA, Messenger; C000605722:FBN1 protein, human; D054392:Adipokines