Constitutional aberrations in the foetus (Carp et al.,

Constitutional chromosomal
aberrations contribute to repeated miscarriage and infertility leading to
reproductive failures in both males and females. These aberrations may show no
obvious clinical manifestations and remain undetected across multiple
generations. However, recurrent/spontaneous pregnancy loss, infertility and/or
genotypic/phenotypic aberrations may be manifested in the progeny. Reproduction
failure can be absolute (infertility, spontaneous abortions, and stillbirths)
or relative (congenital malformation, genetic syndromes and mental
retardation). The cause of almost any reproductive abnormality can be the
result of genetic and physiological events that occur in mother, father and
child (Lungeanu et al.,2007). Recurrent miscarriage
(RM) is defined as the loss of three or more consecutive pregnancies before 20
weeks of gestation and about 60% of RM might be caused by chromosomal aberrations
in the foetus (Carp et al., 2004). It is
considered a multifactorial problem, with different causes involved in its
etiology, including environmental, genetic, anatomical, endocrine,
immunological thrombophilic and infectious diseases (Carp et al., 2001; Hogge et
al., 2003). It is hypothesized that the majority of chromosome abnormalities
detected in spontaneous miscarriages occurs de
novo and results from random errors produced during gametogenesis and
embryonic development (Carvalho et al., 2010).
In females, spontaneous miscarriage is a common problem during pregnancy affecting
25 to 50%, although only 15% of the cases are diagnosed clinically (Warren
and Silver, 2008; Rai and Regan, 2006). Half of the
sporadic early miscarriages (12 weeks gestational age) are caused by fetal
chromosome abnormalities, and nearly one third in second trimester miscarriages
(Goddijn 
et al., 2000). In approximately 3–5% of couples with recurrent
miscarriage, one of the partners is affected by a chromosomal translocation, as
opposed to 0.2% in the normal population (Hirshfeld-Cytron et al., 2001;
Sugiura-Ogasawara et al., 2008). A recent study
reported that 49% of the sporadic miscarriage
samples that had been karyotyped, showed chromosome abnormalities. The spectrum
of these chromosome abnormalities included 86% numerical abnormalities, 6%
structural abnormalities and 8% other chromosome abnormalities like mosaicism,
or double and triple trisomies. In an Indian  study,
chromosomal aberrations were found in 8.57% of patients in which numerical,
structural abnormalities and polymorphic variants were 0.95%, 2.87% and 4.76%,
respectively (Goddijn  et al., 2000;
Rajasekhar et al., 2013).

 

Additionally, infertility
affects approximately 15% of couples during the age of reproduction. There seems to be an
association between genetic abnormalities and infertility in both men and women.
Approximately 40% of the infertility cases are caused due to pathological
conditions of both male and female. , and  20% is related to  the varying age group  (Yoshida  et al., 1996). Majorly of the
infertility in males is contributed by genetic factors including
chromosomal anomalies, gene mutation coupled with impaired
spermatogenesis (Quilter et al., 2003; Whitman-Elia and Baxley, 2001). Several studies have
shown increased chromosomal aberrations in 5-7% of the patients with
oligospermia, and 10-15% in patients with Azoospermia. Among several
etiological factors, chromosomal abnormalities play a significant role in male
infertility showing 10-15% of aberrations. Of these, about  5% are numerical or structural abnormalities
and 80-85% cases are due to sex chromosome anomalies whereas  about 2% are mosaics with autosomal
abnormalities (Patsalis et al., 2002; Siffroi et al., 2000).

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Chromosomal changes include
normal polymorphic variants in addition to major chromosomal abnormalities. Polymorphic variations include varying sizes of
heterochromatin blocks, satellite or repeat sequence regions and inversions (Shaffer
et al., 2009). Common cytogenetic polymorphisms detected by GTG banding
technique are referred to as heteromorphisms. These variation include, increase in length of the heterochromatic regions on the long
arms of chromosomes 1 (1qh+) and 9 (9qh+), an increase in length of the short
arm satellites and stalks of the acrocentric D and G group chromosomes (13, 14,
15, 21 and 22). These are designated, as 13pstk+, 14pstk+, 15pstk+, 21pstk+ and
22pstk+, respectively (Borgaonkar,
1975). Impact
of chromosome heteromorphism has been studied previously in infertility and
recurrent miscarriages, however, the underlined mechanisms need to be clearly
defined (Purandare et al., 2011). The
present study provides a deeper insight to the chromosomal anomalies and
heterochromatic variations inrecurrent/spontaneous abortion and other reproductive
failures in humans. Detection of such anomalies is of fundamental importance
for the diagnosis of infertility, to take up the follow up treatment and the
evaluation for risk in future pregnancy. This is envisaged to culminate into  overall pregnancy management.

 

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