June 30, 1999 -- Researchers have discovered that sons conceived with the aid of a popular in vitro fertilization technique can inherit the same genetic defects that rendered their fathers infertile.
HHMI investigator David Page of the Whitehead Institute for Biomedical Research at Massachusetts Institute of Technology and his colleagues studied three men who fathered sons through a widely used fertilization technique called intracytoplasmic sperm injection (ICSI). In each case, the fathers passed on a Y chromosome genetic defect called an AZFc deletion. Such deletions are the most frequent molecularly defined cause of failure to produce sperm, affecting about five to ten percent of infertile men with insufficient sperm production. The research was published in the July issue of the journal Human Reproduction.
Page also noted that researchers in Taiwan published an article in the June issue of the journal Fertility and Sterility that describes another family in which a son conceived by ICSI inherited the AZFc defect from his father.
In treating AZFc-deficient men with ICSI, clinicians isolate the few sperm that are produced and inject a single sperm directly into an egg. The fertilized egg is then implanted in the mother.
While fertility experts had strongly suspected that the AZFc deletion could
be inherited in such cases, that suspicion had not been clinically confirmed
until now. The finding raises thorny ethical questions about assisted
reproduction techniques. "I think this finding is going to change genetic
counseling," said Page, "because what had been a theoretical concern is now
concrete. Now we have four families, including the one in Taiwan, in which there
are boys who in all likelihood will be infertile as adults." (Girls are
unaffected by the defect, since they receive an X chromosome, rather than the
defective Y chromosome, from their fathers
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Contact: Jim Keeley
keeleyj@hhmi.org
301-215-8858
Howard Hughes Medical Institute
1-Jul-1999