Cytogenetic and molecular evaluation of 241 small supernumerary marker chromosomes: Cooperative study of 19 Italian laboratories

Leda Dalprà, Daniela Giardino, Palma Finelli, Cecilia Corti, Chiara Valtorta, Silvana Guerneri, Patrizia Ilardi, Renata Fortuna, Domenico Coviello, Gianfranco Nocera, Francesco Paolo Amico, Emanuela Martinoli, Elena Sala, Nicoletta Villa, Francesca Crosti, Francamaria Chiodo, Ludovica Verdun Di Cantogno, Elisa Savin, Gianfranco Croci, Fabrizia FranchiGiovanna Venti, Emilio Donti, Valeria Migliori, Antonella Pettinari, Stefania Bonifacio, Claudia Centrone, Francesca Torricelli, Simona Rossi, Paolo Simi, Paola Granata, Rosario Casalone, Elisabetta Lenzini, Lina Artifoni, Vanna Pecile, Sergio Barlati, Daniela Bellotti, Daniele Caufin, Adalgisa Police, Simona Cavani, Giuseppe Piombo, Mauro Pierluigi, Lidia Larizza

Research output: Contribution to journalArticlepeer-review


Purpose: We evaluated the experiences of 19 Italian laboratories concerning 241 small supernumerary marker chromosomes (sSMCs) with the aim of answering questions arising from their origin from any chromosome, their variable size and genetic content, and their impact on the carrier's phenotype. Methods: Conventional protocols were used to set up the cultures and chromosome preparations. Both commercial and homemade probes were used for the fluorescent in situ hybridization analyses. Results: A total of 113 of the 241 sSMCs were detected antenatally, and 128 were detected postnatally. There were 52 inherited and 172 de novo cases. Abnormal phenotype was present in 137 cases (57%), 38 of which were antenatally diagnosed. A mosaic condition was observed in 87 cases (36%). In terms of morphology, monocentric and dicentric bisatellited marker chromosomes were the most common, followed by monocentric rings and short-arm isochromosomes. The chromosomes generating the sSMCs were acrocentric in 132 cases (69%) and non-acrocentric chromosomes in 60 cases (31%); a neocentromere was hypothesized in three cases involving chromosomes 6, 8, and 15. Conclusion: The presented and published data still do not allow any definite conclusions to be drawn concerning karyotype-phenotype correlations. Only concerted efforts to characterize molecularly the sSMCs associated or not with a clinical phenotype can yield results suitable for addressing karyotype-phenotype correlations in support of genetic counseling.

Original languageEnglish
Pages (from-to)620-625
Number of pages6
JournalGenetics in Medicine
Issue number9
Publication statusPublished - Nov 2005


  • Cooperative study
  • Genetic counseling
  • Genotype-phenotype correlations
  • Prenatal diagnosis
  • Supernumerary marker chromosomes

ASJC Scopus subject areas

  • Genetics(clinical)
  • Genetics


Dive into the research topics of 'Cytogenetic and molecular evaluation of 241 small supernumerary marker chromosomes: Cooperative study of 19 Italian laboratories'. Together they form a unique fingerprint.

Cite this