FERTILITY DISORDERS – CHROMOSOMAL CAUSES

Scientific Background

In Germany, approximately 1.4 million adults have an unfulfilled desire to have children over a period of more than one year. According to WHO estimates, the causes of infertility are distributed roughly equally between men and women (30-40%). In about 20% of cases, causes are present in both partners. For 10-15% of affected couples, the cause remains unexplained.

In addition to gynecological, endocrinological, and andrological evaluations, a genetic examination of both partners is usually indicated. The most common chromosomal causes of female fertility disorders include:

• Ullrich-Turner syndrome (primary ovarian failure, short stature)
• Triplo-X syndrome (partial ovarian failure/Climacterium praecox)
• Gonosomal mosaics (approx. 0.7% of cases)
• Reciprocal translocations (approx. 1% of cases)
• Robertsonian translocations (approx. 0.4% of cases)

Chromosomal alterations are found in about 2% of infertile males, or about 10 times more often than in the general male population. The most common chromosomal causes of male infertility include:

• Numerical gonosomal aberrations (e.g., Klinefelter syndrome, approximately 5% of cases)
• Gonosomal mosaics (approximately 0.5% of cases)
• Reciprocal translocations (approx. 1% of cases)
• Robertsonian translocations (approx. 0.6% of cases)

The probability of chromosomal abnormalities increases with the decrease in sperm count. While the rate of chromosomal abnormalities in newborns is about 0.6%, it is 13-15% in males with azoospermia, and 7-10% in males with oligozoospermia (<10 million sperm/ml).