Background: Conventional karyotyping (550 bands resolution) is able to identify chromosomal aberrations >5-10 Mb, which represent a known cause of intellectual disability/developmental delay (ID/DD) and/or multiple congenital anomalies (MCA). Array-Comparative Genomic Hybridization (array-CGH) has increased the diagnostic yield of 15-20%. Results: In a cohort of 700 ID/DD cases with or without MCA, including 15 prenatal diagnoses, we identified a subgroup of seven patients with a normal karyotype and a large complex rearrangement detected by array-CGH (at least 6, and up to 18 Mb). FISH analysis could be performed on six cases and showed that rearrangements were translocation derivatives, indistinguishable from a normal karyotype as they involved a similar band pattern and size. Five were inherited from a parent with a balanced translocation, whereas two were apparently de novo. Genes spanning the rearrangements could be associated with some phenotypic features in three cases (case 3: DOCK8; case 4: GATA3, AKR1C4; case 6: AS/PWS deletion, CHRNA7), and in two, likely disease genes were present (case 5: NR2F2, TP63, IGF1R; case 7: CDON). Three of our cases were prenatal diagnoses with an apparently normal karyotype. Conclusions: Large complex rearrangements of up to 18 Mb, involving chromosomal regions with similar size and band appearance may be overlooked by conventional karyotyping. Array-CGH allows a precise chromosomal diagnosis and recurrence risk definition, further confirming this analysis as a first tier approach to clarify molecular bases of ID/DD and/or MCA. In prenatal tests, array-CGH is confirmed as an important tool to avoid false negative results due to karyotype intrinsic limit of detection.

Large cryptic genomic rearrangements with apparently normal karyotypes detected by array-CGH.

DI GREGORIO, ELEONORA;BIAMINO, ELISA;BELLIGNI, ELGA FABIA;CALCIA, ALESSANDRO;MANCINI, CECILIA;GIORGIO, ELISA;CAVALIERI, Simona;GANDIONE, Marina;MANDRILE, Giorgia;CIRILLO, Margherita;FERRERO, Giovanni Battista;BRUSCO, Alfredo
2014

Abstract

Background: Conventional karyotyping (550 bands resolution) is able to identify chromosomal aberrations >5-10 Mb, which represent a known cause of intellectual disability/developmental delay (ID/DD) and/or multiple congenital anomalies (MCA). Array-Comparative Genomic Hybridization (array-CGH) has increased the diagnostic yield of 15-20%. Results: In a cohort of 700 ID/DD cases with or without MCA, including 15 prenatal diagnoses, we identified a subgroup of seven patients with a normal karyotype and a large complex rearrangement detected by array-CGH (at least 6, and up to 18 Mb). FISH analysis could be performed on six cases and showed that rearrangements were translocation derivatives, indistinguishable from a normal karyotype as they involved a similar band pattern and size. Five were inherited from a parent with a balanced translocation, whereas two were apparently de novo. Genes spanning the rearrangements could be associated with some phenotypic features in three cases (case 3: DOCK8; case 4: GATA3, AKR1C4; case 6: AS/PWS deletion, CHRNA7), and in two, likely disease genes were present (case 5: NR2F2, TP63, IGF1R; case 7: CDON). Three of our cases were prenatal diagnoses with an apparently normal karyotype. Conclusions: Large complex rearrangements of up to 18 Mb, involving chromosomal regions with similar size and band appearance may be overlooked by conventional karyotyping. Array-CGH allows a precise chromosomal diagnosis and recurrence risk definition, further confirming this analysis as a first tier approach to clarify molecular bases of ID/DD and/or MCA. In prenatal tests, array-CGH is confirmed as an important tool to avoid false negative results due to karyotype intrinsic limit of detection.
7
82
1
10
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4247713/
GTG-banding; Array-CGH; Unbalanced derivative chromosomes; CNV; Genomic rearrangement; Intellectual disability
Eleonora, Di Gregorio ; Elisa, Savin; Elisa, Biamino; Elga Fabia, Belligni ; Valeria Giorgia,Naretto ; Gaetana, D’Alessandro; Giorgia, Gai; Franco, Fiocchi; Alessandro, Calcia; Cecilia, Mancini; Elisa, Giorgio; Simona, Cavalieri; Flavia, Talarico; Patrizia, Pappi; Marina, Gandione; Monica, Grosso; Valentina, Asnaghi; Gabriella, Restagno; Giorgia, Mandrile; Giovanni, Botta; Margherita, Cirillo ; Enrico, Grosso; Giovanni Battista, Ferrero ; Alfredo, Brusco
File in questo prodotto:
File Dimensione Formato  
93.Large cryptic genomic rearrangements_Mol citog2014.pdf

accesso aperto

Tipo di file: PDF EDITORIALE
Dimensione 2.36 MB
Formato Adobe PDF
2.36 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2318/151047
Citazioni
  • ???jsp.display-item.citation.pmc??? 10
  • Scopus 21
  • ???jsp.display-item.citation.isi??? 20
social impact