Patterns of Chromosomal Translocations Identified by a Birth Defects Registry, Hawaii, 1986–2000

Abstract

Using a birth defects registry, this investigation examined the distribution of translocations by type of translocation, chromosomes involved in the translocation, pregnancy outcome, method of diagnosis, inheritance, and diagnosis of major structural birth defects. A total of 121 cases were identified through a statewide population-based birth defects registry. The translocations were reciprocal in 89 (73.6%) cases, Robertsonian in 32 (26.4%) cases, balanced in 86 (71.1%) cases, and unbalanced in 35 (28.9%) cases. Live births accounted for 76 (88.4%) of balanced translocations and 22 (62.9%) of unbalanced translocations. Diagnosis was made by amniocentesis or chorionic villus sampling in 72 (83.7%) of balanced translocations and 11 (31.4%) of unbalanced translocations. Of cases of known inheritance, the translocation was of maternal origin in 38 (46.3%) cases, paternal origin in 25 (30.5%) cases, and de novo in 19 (23.2%) cases. Major structural birth defects were diagnosed in 17 (19.8%) of balanced translocations and 20 (57.1%) of unbalanced translocations. Translocations were more likely to be reciprocal, balanced, and of maternal origin. Infants and fetuses with unbalanced translocations were less likely to be live births and diagnosed by amniocentesis or chorionic villus sampling and more likely to be diagnosed with major structural birth defects.

Is Rapid Aneuploidy Screening Used Alone Acceptable in Prenatal Diagnosis? An Evaluation of the Possible Role of Ultrasound Examination

“…Most of them were inherited from a parent. These results are consistent with those in the literature [14,15] . 15.3% (2/12) of the balanced translocations were de novo.…”

“…Unbalanced translocations are associated with congenital abnormalities more often than balanced ones [15] and those not detected antenatally are probably discovered after birth because of their phenotypic consequences. Balanced translocations are generally ignored except by the way of antenatal karyotyping or in adulthood because of reproductive problems or a familial investigation.…”

“…Balanced translocations are generally ignored except by the way of antenatal karyotyping or in adulthood because of reproductive problems or a familial investigation. Women with a balanced translocation have a greater risk of repeated miscarriages and of bearing children with missegregation of the translocation [15,16] . In cases of heritable translocations, genetic counselling must be directed towards future pregnancies because they have the potential to result in unbalanced products.…”