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Epigenetics Chromatin. 2014 Jan 7;7(1):1. doi: 10.1186/1756-8935-7-1.

Telomere shortening and telomere position effect in mild ring 17 syndrome.

Author information

1
Cytogenetics and Molecular Genetics Unit, 'Bambino Gesù' Children's Hospital, IRCCS, Piazza S. Onofrio 4, 00165 Rome, Italy.
2
Department of Biology, University 'Roma Tre', Rome, Italy.
3
Gene Expression-Microarrays Laboratory, 'Bambino Gesù' Children's Hospital, IRCCS, Rome, Italy.
4
Medical Genetics Unit, 'Bambino Gesù' Children's Hospital, IRCCS, Rome, Italy.
5
Neurology Unit, 'Bambino Gesù' Children's Hospital, IRCCS, Rome, Italy.
6
Dermatology Unit, 'Bambino Gesù' Children's Hospital, IRCCS, Rome, Italy.
#
Contributed equally

Abstract

BACKGROUND:

Ring chromosome 17 syndrome is a rare disease that arises from the breakage and reunion of the short and long arms of chromosome 17. Usually this abnormality results in deletion of genetic material, which explains the clinical features of the syndrome. Moreover, similar phenotypic features have been observed in cases with complete or partial loss of the telomeric repeats and conservation of the euchromatic regions. We studied two different cases of ring 17 syndrome, firstly, to clarify, by analyzing gene expression analysis using real-time qPCR, the role of the telomere absence in relationship with the clinical symptoms, and secondly, to look for a new model of the mechanism of ring chromosome transmission in a rare case of familial mosaicism, through cytomolecular and quantitative fluorescence in-situ hybridization (Q-FISH) investigations.

RESULTS:

The results for the first case showed that the expression levels of genes selected, which were located close to the p and q ends of chromosome 17, were significantly downregulated in comparison with controls. Moreover, for the second case, we demonstrated that the telomeres were conserved, but were significantly shorter than those of age-matched controls; data from segregation analysis showed that the ring chromosome was transmitted only to the affected subjects of the family.

CONCLUSIONS:

Subtelomeric gene regulation is responsible for the phenotypic aspects of ring 17 syndrome; telomere shortening influences the phenotypic spectrum of this disease and strongly contributes to the familial transmission of the mosaic ring. Together, these results provide new insights into the genotype-phenotype relationships in mild ring 17 syndrome.

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