Correlation between missed abortion and insertional translocation involving chromosomes 1 and 7

Abstract

Background: Missed abortion (Silent miscarriage) is defined as intrauterine fetal death before twenty weeks gestation. One of the most common causes of early missed abortions (before 10 weeks gestation) is cytogenetic abnormalities.

Objective: To asses if there is a correlation between chromosomal aberrations (especially in chromosome 7) and missed abortion among at least two generations.

Materials and methods: After exclusion of direct causes of missed abortion, this study included 60 women (the study group) who had first trimestric missed abortion and 30 healthy women who did not suffer from any diseases during their pregnancy and had apparently normal outcome (the control group). All cases were diagnosed; the blood and tissue samples were collected from the mothers and abortuses from the Department of Obstetrics and Gynecology, Maternity Hospital, Ain Shams University. Cytogenetic analyses were performed by using conventional technique and G/T banding techniques and Fluorescence In Situ Hybridization (FISH) analysis with a whole chromosome 7 painting probe (WCP7) and a 7q subterminal probe (7q36, qter), prepared by chromosome micro dissection technique was used for confirming the specific chromosomal abnormality.

Results: <insertional translocation between chromosomes 1 and 7 (46, XX, ins. (1; 7) (p32; q32.35). This insertion has appeared in two families and among two generations, and in one family among three generations.

Conclusion: Chromosome 7 insertional translocation is a possible autosomal dominant inherited trait and may cause missed abortion.

Keywords: Fluorescence In Situ Hybridization; Maternal chromosomal aberrations; Missed abortion.

Figure 1

Partial karyotype of the case. A seeming terminal deletion was seen on one chromosome 7. The normal chromosomes are marked by arrows. The derivative chromosomes are marked by arrowhead

Figure 2

Family Pedigree showed dominantly inherited trait through many generations of one family, females are insertion carriers [46, XX, ins. (7:1) (q32.35; p32)]

Figure 3

FISH examination of the case using WCP7 .There is an additional hybridization signal on derivative 1 besides two signals of chromosome 7. It showed that the case was an insertional translocation carrier. The red is counterstain color of PI, The yellow represented the hybridized signals

Figure 4

FISH examination of the case using 7q subterminal probe. There were no additional signals on other chromosomes except on chromosomes 7 .It showed the region 7q36 --qter was not inserted into the chromosome 1. The green is counterstain color of DAPI. The kelly represented the hybridized signals