March 19, 2022

Karyotyping in Couples with Infertility

What is infertility? 

Infertility is defined as the failure of a couple to achieve a clinical pregnancy after 12 months of regular unprotected sexual intercourse. Worldwide around 1 in 6 couples face infertility problems which require further investigation.  

Is infertility genetic?  

It is estimated that approximately 30% of infertility cases are caused by genetic defects, including chromosomal abnormalities, single gene disorders or are due to multifactorial inheritance.  

How common are chromosomal abnormalities in couples with infertility? 

Current studies indicate that the incidence of chromosomal abnormalities in couples with infertility is higher than in the general population and could reach 15%.  

Which is the test that detects chromosomal abnormalities? 

Karyotyping is the test that detects chromosomal abnormalities. It is the representation of an individual’s chromosomes and can identify numerical and structural abnormalities. A normal human karyotype has 46 chromosomes, 44 autosomes and 2 sex chromosomes (ΧΧ for females and XY for males).   

How is karyotyping performed?  

Following blood sampling, peripheral blood lymphocytes are cultured and chromosomes are analyzed using high-resolution G-banding technique under a microscope. It must be emphasized that in couples with infertility, karyotyping of both partners should be performed. 

Which are the main indications for karyotyping in a couple?  

Clinical indications for karyotyping include: 

  • Couples with infertility of unknown etiology  
  • Women with primary or secondary amenorrhea or ovarian insufficiency 
  • Men with sperm abnormalities  
  • Couples with two or more miscarriages or a previous sudden infant death  
  • Family history of multiple miscarriages 

Which are the most common chromosomal abnormalities detected in couples with infertility?  

The most common numerical chromosomal abnormalities in couples with infertility are Klinefelter syndrome (47,XXY) in males and Turner syndrome (45,Χ0) in females. A frequent finding is the low level X chromosome aneuploidy in a mosaic form in women of advanced age, which should be taken into consideration when counselling couples.  

Structural abnormalities include balanced (reciprocal or Robertsonian) translocations and inversions. Although carriers have a normal phenotype, they have a high risk of producing abnormal embryos.  

What are the options of a carrier of a chromosomal abnormality?  

He or she should be offered genetic counselling by a geneticist to help them understand the specific finding and propose available options such as prenatal or preimplantation testing.  

In Genesis Genoma Lab karyotyping is performed by experienced cytogeneticists and appropriate genetic counselling is offered.    

Kouvidi Elisavet, MSc, PhD 

Biologist – Cytogeneticist 

Genesis Genoma Lab