Data on Families of Chromosome Translocation Carriers Ascertained Because of Habitual Spontaneous Abortion
Authors: Smith A. , Gaha T. J. 
Published: February 2008

EDITORIAL COMMENT: This paper confirms the findings of other workers that a chromosomal abnormality in one of the parents (proband) is likely to be associated with a high rate of spontaneous abortion. The incidence of chromosome abnormalities in the large number of aborted conceptuses in this series has not been studied, but the implication of a high incidence can be inferred from other series. Where such chromosomal studies have been done, abnormalities have been shown to consist of unbalanced chromosome abnormalities which are likely to be lethal or simply a balanced state as present in one or other parent.

It is worth emphasizing that chromosome abnormalities in the parents can be found in only a small proportion (no more than 5%) of all habitual spontaneous aborters. Moreover, the vast majority of habitual aborters (70–80%) proceed to have a normal pregnancy with treatments such as immunotherapy, HCG or psychological management, which obviously have no effect on established chromosomal abnormality.

In selecting patients for intensive antenatal diagnosis and possible treatment, it is imperative that strict criteria of selection be enjoined. The chances of a normal full‐term pregnancy after only 2 consecutive miscarriages is in the region of 80% and therefore, most investigators would insist on 3 consecutive miscarriages before investigating further any underlying problem. Even after 3 consecutive miscarriages, the chances of a normal pregnancy is 55–60%. In such patients, it is however mandatory to rule out chromosomal abnormalities before any other treatment is contemplated. The value of this paper is in emphasizing that certain familial tendencies to increased fetal loss could be based on demonstrable chromosome changes and these couples must be identified so that adequate antenatal diagnosis and advice be given.

Maurice M. Cauchi

Head, Haematology/Immunology Section

Royal Women's Hospital, Melbourne

Summary: Cytogenetic studies were performed on 1,180 individuals — 490 couples + 200 females presenting with habitual spontaneous abortion (HSA). These revealed 24 abnormal results (2.03%) — 15 were apparently balanced reciprocal translocations and 9 were Robertsonian translocations. Of 97 pregnancies among the translocation carriers, there were 10 living children and 87 pregnancy losses — a loss rate of 89.7%. There were 11 familial translocations. In 10 familial cases with a full family tree, there were 27 spontaneous abortions and 64 livebirths among the 30 adult translocation carrier relatives — a loss rate of 29.6%. This is twice the risk found in the general population but not as high as in the probands, who had 6 times the abortion rate in the general population. Mechanisms are suggested for this difference. The subsequent pregnancy history of 12 index translocation couples showed an apparently improved pregnancy outcome with 13 further fetal losses and 13 living children, over a follow‐up time per patient ranging from 1–5.5 years. However, when the pregnancy losses at ascertainment were combined with postascertainment losses, the overall rate of pregnancy loss remained the same.