Observed versus expected rates of unbalanced fetal karyotype at second trimester amniocentesis when one parent carries a balanced translocation

Nuchal translucency thickness in the prediction of unbalanced translocations

OBJECTIVE

The aim of this study was to assess the role of nuchal translucency (NT) in the prediction of unbalanced translocation in offspring of couples in which one of the parents is a balanced translocation carrier.

MATERIAL AND METHODS

From January 1996 to December 2012, fetal NT was measured before chorionic villus sampling in 86 pregnancies referred because of parental balanced translocation.

RESULTS

No significant differences in pregnancy characteristics and in NT expressed in millimetres or in multiples of the median (MoMs) were observed between the 41 fetuses with a normal karyotype [1.72 mm, 95% confidence interval (CI): 1.49-1.96; 1.14 MoM; 95% CI: 1.01-1.26], the 38 fetuses with balanced translocations (1.78 mm, 95% CI: 1.44-2.12; 1.22 MoM; 95% CI: 1.01-1.43) and the 7 fetuses with unbalanced translocations (2.21 mm, 95% CI: 1.33-3.09; 1.59 MoM; 95% CI: 0.72-2.45). The proportions of fetuses with NT above 95th centile in the three groups were 9.1% in fetuses with normal karyotype, 18.4% in balanced translocations and 28.6% in unbalanced translocations, not significantly different.

CONCLUSION

Although a trend to an increased NT was observed in fetuses with unbalanced translocation, no significant differences were reached. According to our results, a normal NT evaluation should not preclude the performance of CVS in pregnancies of balanced translocation parents.

Severe hypospadias associated with Robertsonian translocation

In this study, we report a 3-year-old boy with severe scrotal hypospadias with Robertsonian translocation [45,XY,t(13q;14q)]. The patient was born at term with a low birth weight and hypospadias. There was no endocrinological abnormality. His father also has a balanced 13-14 Robertsonian translocation. Two-stage hypospadias repair was carried out. The presence of this chromosomal anomaly and hypospadias are unique to our patient, compared to others with the 45,XY,t(13q;14q) translocation. Although no such association has been reported so far, we thought that severe hypospadias in this case might be associated with this translocation.