Prenatal detection by subtelomeric FISH and MLPA of unbalanced meiotic recombinants resulting from parental pericentric inversions.
OBJECTIVE
Pericentric inversion carriers are predisposed to produce unbalanced gametes that result in conceptuses having either a partial trisomy for one distal segment and a partial monosomy for the other or vice versa. Larger inversions result in smaller unbalanced distal segments and a higher likelihood of a viable fetus. In these cases the structure of the recombinant chromosome is similar to the original balanced inverted or normal ones despite the (unbalanced) genetic content. Such cases may not be detected prenatally by conventional cytogenetic analysis.


METHODS
In all prenatal samples from the pericentric inversion carriers we applied subtelomeric FISH probes specific for the chromosome involved in order to detect parental meiotic recombinants resulting from a single cross-over event. Confirmatory MLPA was also applied in unbalanced fetuses.


RESULTS
The occurrence of a duplication deficiency unbalance from pericentric inversion carriers was successfully detected in all three fetuses by FISH. MLPA assays applied in two cases confirmed these results.


CONCLUSIONS
The application of commercial FISH subtelomeric probes is a reliable method that could be routinely applied for the detection of single cross-over meiotic recombinants. MLPA is a sound alternative technique.
Grati
Francesca R
FR
Research and Development, Cytogenetics and Molecular Biology, TOMA Advanced Biomedical Assays S.p.A., Via Ferrer 25/27, 21052 Busto Arsizio, Varese, Italy. fgrati@tomalab.com
Chinetti
Sara
S
Malgara
Roberta
R
Rognoni
Giulia
G
Grimi
Beatrice
B
De Toffol
Simona
S
Milani
Silvia
S
Dulcetti
Francesca
F
Frascoli
Giuditta
G
Di Meco
Anna Maria
AM
Liuti
Rosaria
R
Trotta
Anna
A
Coffa
Jordy
J
Maggi
Federico
F
Simoni
Giuseppe
G
D007446:Chromosome Inversion; D020732:Cytogenetic Analysis / Q000379:methods; D005260:Female; D005333:Fetus / Q000502:physiology; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D007621:Karyotyping; D008297:Male; D008540:Meiosis / Q000235:genetics*; D011296:Prenatal Diagnosis / Q000379:methods*; D011995:Recombination, Genetic; D016615:Telomere / Q000235:genetics