balanced translocation

the balanced translocation whose offspring would be at risk.
Abnormalities resulting from an unbalanced reciprocal
translocation depend on the particular chromosomal fragments
that are present in monosomic or trisomic form. Sometimes
spontaneous abortion is inevitable; at other times a child with
multiple abnormalities may be born alive. Clinical syndromes
have been described due to imbalance of some specific
chromosomal segments. This applies particularly to terminal
chromosomal deletions. For other rearrangements, the likely
effect can only be assessed from reports of similar cases in the
literature. Prediction is never precise, since reciprocal
translocations in unrelated individuals are unlikely to be
identical at the molecular level and other factors may influence
expression of the chromosomal imbalance. The risk of an
unbalanced karyotype occurring in offspring depends on the
individual translocation and can also be difficult to determine.
An overall risk of 5–10% is often quoted. After the birth of one
affected child, the recurrence risk is generally higher (5–30%).
The risk of a liveborn affected child is less for families
ascertained through a history of recurrent pregnancy loss
where there have been no liveborn affected infants.
Pregnancies at risk can be monitored with chorionic villus
sampling or amniocentesis.