A homozygous frameshift mutation in the ESCO2 gene: Evidence of intertissue and interindividual variation in Nmd efficiency
Article first published online: 14 JUN 2006
Copyright © 2006 Wiley-Liss, Inc.
Journal of Cellular Physiology
Volume 209, Issue 1, pages 67–73, October 2006
How to Cite
Resta, N., Susca, F. C., Di Giacomo, M. C., Stella, A., Bukvic, N., Bagnulo, R., Simone, C. and Guanti, G. (2006), A homozygous frameshift mutation in the ESCO2 gene: Evidence of intertissue and interindividual variation in Nmd efficiency. J. Cell. Physiol., 209: 67–73. doi: 10.1002/jcp.20708
- Issue published online: 26 JUL 2006
- Article first published online: 14 JUN 2006
- Manuscript Accepted: 8 MAY 2006
- Manuscript Received: 23 JAN 2006
- Fondazione Cassa di Risparmio di Puglia “Progetto integrato per la salvaguardia della salute dell'uomo”
Roberts syndrome (RS) is a rare disorder characterized by tetraphocomelia and several other clinical features. Cells from RS patients exhibit characteristic premature separation of heterochromatic region of many chromosomes and abnormalities in cell cycle. Mutations in the ESCO2 gene have recently been identified in 20 RS families. We performed mutational analysis of the ESCO2 gene in two fetuses diagnosed with RS and their normal parents. In both fetuses, we identified homozygosity for the c. 745_746delGT mutation, while the non-consanguineous parents were both heterozygous for the same mutation. Considering the position of the mutation identified, we carried out qualitative and quantitative real-time ESCO2 cDNA analysis on RNA isolated from CVS-stromal cells in one fetus, amniocytes in the second fetus, and lymphocytes from the heterozygous parents. The results of this analysis showed that despite the presence of a premature termination codon (PTC) 112 nucleotides upstream of the next exon3–exon4 junction, the mutant ESCO2 mRNA was present in both fetuses, albeit at low levels, indicating a partial resistance to nonsense mediated decay (NMD). Interestingly, when cells derived from the two fetuses were treated with an inhibitor of translation, they revealed the presence of tissue and individual variability in NMD efficiency, despite the identical mutational status. The existence of such a variation in the NMD efficiency could explain the broad intrafamilial and interfamilial variability in the clinical presentation of RS patients, and in other genetic diseases where nonsense mutations are responsible for most of the mutation load. Moreover, considering that a mutated full length mRNA was produced in both fetuses, we used Western blot analysis to demonstrate the absence of the ESCO2-truncated protein in cells derived from both fetuses and in a lymphoblastoid cell line derived from the parents. J. Cell. Physiol. 209: 67–73, 2006. © 2006 Wiley-Liss, Inc.