Chinese researchers are reporting that the use of in vitro fertilization (IVF) or another assisted fertility technique called that is called intracytoplasmic sperm injection (ICSI) to conceive appears to increase the odds of Y-chromosome defects or “microdeletions” in male offspring. Although this study was small, it “at least sounds an alarm about the genetic safety of assisted reproductive technology,” the investigators conclude.
This means that the chromosomal defects, or deletions, could result in defective sperm production and possibly also hypospadias. Hypospadia is a relatively common congenital malformation of the male sex organs in which the urinary outlet, or urethra, does not open through the glans of the penis, but rather, develops on the underside of the penis. This defect makes it difficult for the patient to urinate normally and to control one’s stream of urine. Generally, hypospadia occurs because of a hormonal imbalance or deficiency that takes place at a critical point in fetal development prior to birth. Early corrective surgery is generally called for before the child reaches the age of three.
Prior research has linked assisted reproductive technologies such as IVF and ICSI with low birth weight, pre-term delivery, cerebral palsy, and major birth defects. Because of this, some researchers believe that such therapies may prompt gene mutations. In this new study, Dr. He-Feng Huang, from Zhejiang University, and colleagues worked to find answers to this issue by testing for genetic mutations in 19 male infants who were conceived through IVF, 18 who were conceived through ICSI, and 60 baby boys were were conceived naturally. In addition, the fathers of the infant boys were also tested. Because the researchers were hoping to isolate the impact of the fertility treatment, they only studied those infants whose parents had a normal genetic background.
Huang and his colleagues found Y-chromosome microdeletions in one infant conceived with IVF, representing 5.3 percent of the population tested. Microdeletions were also found in three baby boys conceived with ICSI, which represented 16.7 percent of the population tested. By contrast, no Y-chromosome deletions were seen in the control group. The report also indicated that one of the four infants with microdeletions had hypospadias.
The investigators noted that this study is not the first to link ICSI with hypospadias; however, the mechanism has been unclear in the earlier studies. The new findings suggest that the association may be mediated through Y-chromosome microdeletions.
ICSI has long been the main method used to overcome male infertility and its use is on the rise. With ICSI, a single sperm is injected directly into a single egg. If successful fertilization occurs, the embryo is then placed into the female—in IVF treatment—to undergo development as usual. Fertilization rates—which are not the same as pregnancy rates—are relatively high when ICSI is employed with approximately 75%-80% of all eggs manipulated through ICSI becoming fertilized.
Larger studies “should be conducted to confirm our preliminary results,” the researchers conclude.
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