Chromosomal abnormalities in couples with recurrent spontaneous miscarriage: a 21-year retrospective study, a report of a novel insertion, and a literature review

Abstract

Purpose: The aim of this study is to evaluate the frequency and nature of chromosomal abnormalities in Moroccan couples with recurrent spontaneous miscarriage (RSM). In addition, the data were compared with those reported elsewhere in order to give a global estimation of chromosomal abnormalities frequencies.

Methods: The study was performed for all couples with RSM who were referred to the cytogenetic department, Pasteur Institute of Morocco, from different hospitals in Morocco between 1996 and 2016. Cytogenetic analysis was performed according to the standard method.

Results: Among 627 couples with RSM, the chromosomal abnormalities were identified in 11.00% of couples, with chromosomal inversions in 4.30%, reciprocal translocations in 2.71%, Robertsonian translocations in 1.43%, and deletion, isochromosome, and insertion in 0.15% each. The insertion identified [46,XX,ins(6)(p24q21q27)] is new, and is the fourth reported in association with RSM. The mosaic karyotypes were observed in 0.64%, polymorphic variants were identified in 1.27%, and numerical aneuploidy was observed in 0.15%. In regrouping our results with those in 27 other studies already published in 21 different countries, we obtained the frequency of chromosomal abnormalities in couple with RSM to be 5.16% (991/19197 couples). The reciprocal translocation was the most frequent with 2.50%, followed by Robertsonian translocation 0.83% and inversions 0.77%. The other types of chromosomal abnormalities were present with 0.98% in the world.

Conclusion: This data showed that the frequency of chromosomal abnormalities in Moroccan couples with RSM is 11.00%, and in regrouping our results with other studies, the frequency changes to 5.16%.

Keywords: Chromosomal abnormalities; Insertions; Inversions; Reciprocal translocations; Recurrent spontaneous miscarriage (RSM); Robertsonian translocations.

Fig. 1

Frequency of various chromosomal abnormalities and distribution of chromosomes involved in RSM. a Frequency of various chromosomal abnormalities in couples with RSM. b Gender distribution of various chromosomal abnormalities in couples with RSM. c Distribution of p and q arm chromosome involved in RSM. Inv, inversion; RT, reciprocal translocation; PV, polymorphic variation; Rob, Robertsonian translocation; Mos, mosaicism; Del, deletion; Ins, insertion; Iso, isochromosome; NA, numerical aneuploidy

Fig. 2

Frequency of various chromosomal abnormalities observed in different studies by region. a Distribution of chromosomal abnormalities frequencies in couples with RSM by region. b Distribution of reciprocal translocation frequencies in couples with RSM by region. c Distribution of Robertsonian translocation frequencies in couples with RSM by region. d Distribution of chromosome inversion frequencies in couples with RSM by region. e Distribution of various chromosomal abnormalities in the world. Blue, highest frequency; brown, mean frequency; gray, lowest frequency

Fig. 3

Human chromosome ideograms showing regions of reciprocal translocation identified in different studies. The red indicates regions of reciprocal translocation identified in Morocco, the pink in the Sultanate of Oman [17], the aqua in Turkey [31], the green in India [27, 36], the yellow in India and Turkey [27, 31, 36], the orange in India and the Sultanate of Oman [17, 27, 36], and finally the brown in the Sultanate of Oman and Turkey [17, 31]