brosis transmembrane regulator
mutation and congenital bilateral absence of the
vas deferens: a bad combination for successful
intracytoplasmic sperm injection outcomes
brosis (CF) is an autosomal recessive disease
commonly found in Caucasians, and
F508, a major muta-
tion in the gene that encodes cystic
brosis transmembrane
regulator (CFTR), can be identi
ed in over 75% of patients
with CF. Beyond knowing that CFTR promotes a channel
that conducts both Cl
and HCO
, it is unclear how mutations
in the gene encoding this protein can result in male infertility.
An early study on CF adults with azoospermia revealed
congenital bilateral absence of the vas deferens (CBAVD) in
all men
It is speculated that CFTR has an important role in sperm
function well beyond CBAVD and CF. In the study by Lu et al.
, sperm obtained from men with both CFTR mutations and
CBAVD were associated with an increased risk of miscarriage
and stillbirth after intracytoplasmic sperm injection (ICSI) as
compared with men without either CFTR or CBAVD. It is inter-
esting that two recent studies from the People
s Republic of
China have also demonstrated an association between CFTR
and sperm function. One study shows decreased motility
and fertilizing capacity in sperm obtained from elderly men
with CFTR mutations
. The other study, which evaluated
men with azoospermia, observed down-regulation of CFTR
in testicular samples,
again indicating a bigger role for
CFTR in male fertility beyond CBAVD and CF.
In the Lu et al.
study, the prevalence of CFTR muta-
tions in the female partners is not clear because they were
not tested. It is important to test the female partner as well
for CFTR gene abnormalities before performing ICSI using
sperm from a man with either CBAVD or a known CFTR mu-
tation because of the risk that she may also be a carrier. Infor-
mation on mutations and carrier status is important for
counseling the couple regarding the future risk of CF in
offspring as well as the health effects of CFTR mutations
Ranjith Ramasamy, M.D.
Larry I. Lipshultz, M.D.
Baylor College of Medicine, Houston, Texas
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VOL. 101 NO. 5 / MAY 2014