Parental Miscarriages and balanced chromosomal anomalies

ABSTRACT

We estimate at 15% the number of pregnancies that do not succeed to term and 1% the proportion of couples who have at least three miscarriages consult in gynaecology, thus answering the usual definition of the abortive disease. The balanced chromosomal anomalies constitute one of the reasons of the repeated spontaneous abortions. The chromosomal translocations robertsonian or reciprocal are the most the anomalies observed, because they predispose to the production of genetically not balanced gamete and non viable fetuses. We report 5 observations of couples having repeated miscarriages secondary to balanced translocations at one the parents, among the 400 couples followed in the consultation of medical genetics from 1992 to 2004. The karyotype has been achieved at the couples with at least three miscarriages. We identified 5 chromosomal abnormalities two reciprocal translocations t[7;8]; t[l;15] and three robertsonian translocations t[22q22q]; t[14;21]; t[13;14]. The genetic advice is according to the type of the translocation, the localization of the points of break and also of the viability or not of the malformed fetus. It aims to explain to the couples the mechanism responsible for the failure of reproduction, to make them understand them the inefficiency of the hormonal treatment and the theoretical possibilities to lead pregnancies to term. It also permits to estimate the risk of birth to a sick child and to propose to the parents the different means of follow-up of these much desired pregnancies. In this work, we discuss the mechanism by which these anomalies produce the miscarriages and the interest of the chromosomal analysis at the couples who consult for an abortive disease