Indian Journal of Human Genetics Medknow Publications on behalf of Indian Society of Human Genetics ISSN: 0971-6866 EISSN: 1998-362x Vol. 13, Num. 1, 2007, pp. 26-29

Indian Journal of Human Genetics, Vol. 13, No. 1, January-April, 2007, pp. 26-29

Original Article

Impact of pericentric inversion of Chromosome 9 [inv (9) (p11q12)] on infertility

Mozdarani Hossein, Meybodi Anahita Mohseni, Karimi Hamideh

Department of Medical Genetics, School of Medical Sciences, Tarbiat Modares University, Tehran
Correspondence Address:Department of Medical Genetics, School of Medical Sciences, Tarbiat Modares University, Tehran, P.O. Box 14115 - 111, mozdarah@modares.ac.ir

Code Number: hg07005

Abstract

Keywords: Infertility, inversion 9, Iranian population, metaphase analysis

Introduction

Materials and Methods

The patient population consisted of those Iranian couples who attended the infertility clinic. A total of 601 patients with at least three years of infertility were examined. The age of the referred wives ranged from 21-38 years, while the age of the husbands ranged from 25-42 years.

Cytogenetic analysis was performed with GTG banding technique for their lymphocytes.

G-banded chromosomes from peripheral blood were prepared according to the modifications of Verma and Babu. ^[11] Whole complete blood cultures were set up in 10 ml culture tubes. The medium had the following composition: 100 ml RPMI medium (Sigma) supplemented with 20 ml fetal calf serum (Gibco BRL), 1.2 ml Glutamine (Sigma), 1 ml phytohaemagglutinine (Sigma) and penicillin streptomycin (Sigma) mix was added. Five to ten drops of heparinized blood were added to 5 ml of the complete media. Culture tubes were incubated for 72h in a slanting position at 37°C. Colcemid (Sigma) was added at 4 µg/ml to the cultures 2h before harvesting. Slides were prepared after hypotonic treatment of the cells with KCl (0.075 M) followed by fixation in ethanol/glacial acetic acid (3/1 vol/vol). A concentrated suspension of the cells was dropped on slides, which were dried on a slide warmer at 60°C for a few seconds. G-banded chromosomes were obtained by keeping the slides in an oven at 55-60°C then treating them with trypsin solution and stained in 4% Giemsa solution (Merck), dried and examined microscopically using the image analyzer programmed (Cytovision, version 2000, Applied Imaging). Metaphases were karyotyped and interpreted according to the international system for human cytogenetic nomenclature (ISCN). ^[12]

Results

A total of 601 patients with at least three years of infertility were examined. The age of the referred wives ranged from 21-38 years, with a mean of 27.81 years (SD ± 5.276), while the age of the husbands ranged from 25-42 years, with a mean of 32.09 years (SD ± 5.665). There was no significant correlation between the age and pericentric inversion of Chromosome 9. Using the G-banded technique among the 601 patients, 15 (2.5%) individual was found to have inversion 9 (p11q12). Inversion 9 was observed for just 1(0.33%) female, while it was seen in 14 cases of males (4.69%).

Only one case had the break point of (p11q13) which has not considered in statistical analysis.

The incidence of inversion 9 in male patients was found significantly higher than that in female partners (P< 0.05). The total average amount of inversion in both male and females in this study (2.5%) is not significantly higher than normal population [Table - 1], [Figure - 1].

Discussion

A summary of reports for various abnormalities associated with pericentric inversion 9 (p11q13) and (p11q12) is shown in [Table - 2]. The finding of homozygosity for a pericentric inversion of Chromosome 9 is rare ^[5] and none of our cases was homozygote. We have observed 2.5% inversion 9 in cases with infertility which is similar to the earlier report by Sasiadek et al^[13] in the cases of recurrent spontaneous abortions. However, our results cannot be compared to normal or general population because the rate of inv (9) is reported in a wide range from 1-3% by other investigators. ^{[5],[6],[7],[8],[9]}

The major observations in this study was the difference of the rate of inv (9)(p11q12) between the male and female patients as shown in [Table - 1] and [Figure - 1]. In contrast to some other studies on inversions of other chromosomes, ^[14],[15] there is considerable difference in frequency of inv (9) among two sexes (P< 0.05).

These results of inv (9) may explain some idiopathic male infertility. In fact pairing in spermatogenesis constitutes the main problem in inversion heterozygosis. This phenomenon can be more effective in male partners because of their higher rate of meiotic division. An odd number of crossover events (during the pachytene stage of meiosis I) within the inversion segment can lead to two monocentric recombinants with reciprocal duplications/deficiencies in the sperms, ending up in a risk of inheriting such an imbalance when conception occurs. However, it has been shown that the classical assumption that loops are invariably present at meiotic prophase to realize a homologous pairing in inversion heterozygotes ^{[16],[17],[18],[19],[20],[21]} however, the other reports do not agree. ^[22] These results indicate that inv (9) may often cause clinical problems in offspring of the carriers and infertility with sex related unknown certain mechanism.

Acknowledgment

References

Copyright 2007 - Indian Journal of Human Genetics

The following images related to this document are available:

Photo images