Prenatal search for UPD 14 and UPD 15 in 83 cases of familial and de novo heterologous Robertsonian translocations.
OBJECTIVE
The presence in the conceptus of a Robertsonian translocation predisposes to UPD formation, mainly by post-zygotic events of chromosome abnormality rescue. This is due to the increased risk of generating aneuploid zygotes because the rearranged chromosome and the respective homologues are prone to non-disjunction errors. Given this, carriers and karyotypically normal individuals conceived from a parent with a Robertsonian translocation are at risk for UPD. Abnormal phenotypes due to an imprinting effect have been found to be associated with UPD 14 and 15. The aim of the study was to refine, at the time of prenatal diagnosis, the risk for UPD 14 and 15 in a population with Robertsonian translocations involving these chromosomes.


METHODS
Sixty-five cases of familial and de novo heterologous Robertsonian translocations involving chromosomes 14 and 15 and 18 fetuses with a normal karyotype, but conceived by a Robertsonian translocation carrier were prenatally studied to investigate the presence of UPD for chromosomes 14 and 15.


RESULTS
Of the 65 Robertsonian translocation carriers, one fetus with a de novo der(14;21) showed maternal UPD 14. None of the 18 fetuses with a normal karyotype had UPD.


CONCLUSIONS
Our data, combined with other previous prenatal investigations provide a general risk estimate for UPD 14 and 15 of 0.6%. Nevertheless, combining our data and those previously reported, all three fetuses with UPD had a de novo Robertsonian translocation, thus suggesting a risk of UPD formation of about 3% for this specific group of translocation carriers.
Ruggeri
Anna
A
Units of Cytogenetics and Molecular Biology, TOMA Laboratory, Via Ferrer 25/27, 21052 Busto Arsizio, Varese, Italy. toma@tread.it
Dulcetti
Francesca
F
Miozzo
Monica
M
Grati
Francesca R
FR
Grimi
Beatrice
B
Bellato
Silvano
S
Natacci
Federica
F
Maggi
Federico
F
Simoni
Giuseppe
G
D000653:Amniotic Fluid / Q000166:cytology; D002478:Cells, Cultured; D002824:Chorionic Villi / Q000737:chemistry; D002883:Chromosomes, Human, Pair 14 / Q000235:genetics*; D002884:Chromosomes, Human, Pair 15 / Q000235:genetics*; D020732:Cytogenetic Analysis; D004247:DNA / Q000032:analysis; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000737:chemistry; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012307:Risk Factors; D014178:Translocation, Genetic / Q000235:genetics*; D024182:Uniparental Disomy / Q000235:genetics*
D004247:DNA