Reciprocal translocations: a trap for cytogenetists?
We report four cases of subjects with phenotypic abnormalities and mental retardation associated with apparently balanced translocations, two inherited and two de novo, which showed, by molecular analysis, a hidden complexity. All the cases have been analyzed with different molecular techniques, including array-CGH, and in two of them the translocation breakpoints have been defined at the level of base pairs via studies in somatic hybrids containing single derivative chromosomes. We demonstrated that all the translocations were in fact complex rearrangements and that an imbalance was present in three of them, thus accounting for the phenotypic abnormalities. In one case, a Prader-Willi subject, we were not able to determine the molecular cause of his phenotype. This study, while confirming previous data showing unexpected complexity in translocations, further underscores the need for molecular investigations before taking for granted an apparently simple cytogenetic interpretation.
Ciccone
Roberto
R
Biologia Generale e Genetica Medica, Università di Pavia, Pavia, Italy.
Giorda
Roberto
R
Gregato
Giuliana
G
Guerrini
Renzo
R
Giglio
Sabrina
S
Carrozzo
Romeo
R
Bonaglia
Maria Clara
MC
Priolo
Emanuela
E
Laganà
Carmelo
C
Tenconi
Romano
R
Rocchi
Mariano
M
Pramparo
Tiziano
T
Zuffardi
Orsetta
O
Rossi
Elena
E
D000015:Abnormalities, Multiple / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D002869:Chromosome Aberrations; D005260:Female; D015321:Gene Rearrangement; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D011218:Prader-Willi Syndrome / Q000235:genetics; D014178:Translocation, Genetic