Chromosomal variants and male fertility

A case-control study identifying chromosomal polymorphic variations as forms of epigenetic alterations associated with the infertility phenotype

OBJECTIVE

To study the association of chromosomal polymorphic variations with infertility and subfertility.

DESIGN

A comparative case-controlled association study using cytogenetic techniques to compare the frequency of chromosomal variations in infertile individuals versus fertile controls.

SETTING

Department of Infertility Management and Assisted Reproduction, Jaslok Hospital and Research Centre, Mumbai, India.

PATIENT(S)

760 infertile individuals and 555 fertile controls.

INTERVENTION(S)

ICSI, IUI, karyotyping, inverted 4',6-diamidino-2-phenylindole (DAPI), CBG banding.

MAIN OUTCOME MEASURE(S)

Frequency of chromosomal polymorphic variations in infertile individuals undergoing infertility treatment versus fertile individuals.

RESULT(S)

A highly statistically significant increase in the frequency of total chromosomal variants in infertile women (28.31% vs. 15.16%) and infertile men (58.68% vs. 32.55%) was observed. The frequency of 9qh+ was statistically significantly increased in women with primary infertility (16.22% vs. 6.41%) and in men with severe male factor infertility (14.69% vs. 4.25%). A highly statistically significant increase in the frequency of Yqh+ was observed in men whose wives had a bad obstetric history (30.20% vs. 12.74%).

CONCLUSION(S)

The statistically significantly higher incidence of heterochromatic variations found in infertile individuals stresses on the need to evaluate their role in infertility and subfertility. Potential epigenetic, genetic, and chromosomal modifications could be associated with certain complex disorders such as infertility and bad obstetric history.

Reciprocal translocation t(7;16)(q21.2;p13.3) in an infertile man

OBJECTIVE

To report the first case of reciprocal translocation t(7;16)(q21.2;p13.3) associated with male factor infertility.

DESIGN

Case report.

SETTING

University genetics laboratory and university andrology unit.

PATIENT(S)

A 38-year-old man with infertility and oligoasthenoteratozoospermia, but otherwise healthy.

INTERVENTION(S)

Chromosome analyses from peripheral blood lymphocyte cultures using Giemsa (G)-banding (GTG) and C-banding (CBG) and fluorescent in situ hybridization (FISH) were performed.

MAIN OUTCOME MEASURE(S)

Sperm count, motility, morphology, GTG and CBG banding, and FISH.

RESULT(S)

We report an apparently unique reciprocal translocation t(7;16)(q21.2;p13.3) confirmed by FISH in an infertile man. Semen analyses showed oligoasthenoteratozoospermia, with sperm count ranging from 2 x 10(6)/mL to 5 x 10(6)/mL and head defects (98%) in sperm morphology.

CONCLUSION(S)

In the present patient the breakpoint at 16p13.3 could have disrupted or harbored the PRM1, PRM2, or TNP2 genes responsible for the replacement of the histones involved in packaging the DNA into the sperm head. Resulting haploinsufficiency of these genes is likely to be the cause of sperm head defects and infertility in the patient. This case supports the opinion that alterations in the expression of protamine genes may be one of the causes of male factor infertility.

Is there a possible correlation between chromosomal variants and spermatogenesis?

AIM

Heterochromatin polymorphism is considered a variant of a normal karyotype but is more frequent in infertile men. The aim of this study was to evaluate the correlation between heterochromatic variants and male infertility and to discuss the possible mechanisms of how heterochromatic polymorphism might affect spermatogenesis.

METHODS

Cytogenetic analysis was undertaken in 210 infertile males who had been taken into assisted reproductive techniques and in 183 men with proven fertility. Additionally, C-banding was performed in men with heterochromatin polymorphism. Sperm fluorescence in situ hybridization (FISH) was applied in 54 men with normal karyotype presenting either normal or abnormal sperm parameters as well as in 8 men with heterochromatin polymorphism. The outcomes of assisted reproductive techniques were compared between infertile men with normal karyotype and men with heterochromatin polymorphism.

RESULTS

The incidence of heterochromatin polymorphism was higher in infertile men. The most frequent chromosome involved in heterochromatin polymorphism was chromosome 9. Sperm FISH analysis revealed an increased rate of aneuploidy in men with heterochromatin polymorphism. Laboratory and clinical outcomes in assisted reproductive techniques were compromised in men with heterochromatin polymorphism.

CONCLUSIONS

An increased rate of heterochromatin polymorphism in infertile males seems to be more than an incidental finding, and must not be considered as a normal variant. Polymorphic heterochromatin may have deleterious effects on the genetic constitution of spermatozoa. More attention must be directed to infertile men with heterochromatin polymorphism.

Familial hypogonadism with a balanced reciprocal 1;12 translocation

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