Study of Spectrum of Chromosomal Rearrangements in Recurrent Pregnancy Loss

Introduction

Recurrent pregnancy losses (RPLs) are seen in up to 15-20% of all clinically recognized pregnancies, 1-2% of women in general population. Repeated losses are seen in 5-10% of women. The prevalence of chromosomal rearrangements is 6.65% in couples with repeated pregnancy losses. Two to 4% of RPL are associated with parental balanced reciprocal and Robertsonian translocations.

Materials and Methods

The study was conducted at a tertiary care hospital in New Delhi, and in total, 204 couples with RPL enrolled in the study.

Results

In total, 4490 couples presented to the obstetric clinic, of which 204 (4.5%) couples had repeated pregnancy losses. Cytogenetic analysis was done in 198 couples. Out of total 198 patients, 14 patients (7.1%) had cytogenetic alterations. Most common aberrations observed were structural rearrangements, of which reciprocal translocations were more common. In our study cohort, all the couples had maternal age of ≤ 35 years and all the alterations were seen either in mother or in both parents.

Discussion

Our study highlights that cytogenetic alterations not only are common in first trimester miscarriages, but are an important event in miscarriages presenting at later period of gestation and in young mothers as well.

Unbalanced X;Autosome Translocations May Lead to Mild Phenotypes and Are Associated with Autoimmune Diseases

Unbalanced X;autosome translocations are a rare occurrence with a wide variability in clinical presentation in which the X chromosome unbalance is usually mitigated by a favorable X inactivation pattern. In most cases, this compensation mechanism is incomplete, and the patients show a syndromic clinical presentation. We report the case of a family with 4 women, of 3 different generations, carrying an unbalanced X;7 translocation with a derivative X;7 chromosome and showing a skewed X inactivation pattern with a preferential activation of the normal X. None of the carriers show intellectual disability, and all of them have a very mild clinical presentation mainly characterized by gynecological/hormonal issues and autoimmune disorders. We underline the necessity of family testing for a correct genetic consultation, especially in the field of prenatal diagnosis. We indeed discuss the fact that X;autosome translocations may lead to self-immunization, as skewed X chromosome inactivation has already been proved to be related to autoimmune disorders.