Improved detection of cystic fibrosis mutations in infertility patients with DNA sequence analysis.
BACKGROUND
Accurate determination of mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene is critical for genetic counselling and treatment of obstructive azoospermia. Of concern is that detection rates with routine CFTR mutation panels vary widely depending on patient ancestry; and such panels have limited value for azoospermic patients, who are more likely to carry rare mutations. An alternative approach offers comprehensive, CFTR mutation analysis by a DNA sequence method. We investigated whether this method could improve CFTR detection rates in men with obstructive azoospermia in a prospective study of men with obstructive azoospermia and their partners who were referred for genetic counselling and testing at one of two institutions.


METHODS
Sixteen patients with congenital absence of the vas deferens (CAVD, n = 14) or idiopathic obstructive azoospermia (n = 2) were studied. DNA from all patients was analysed for mutations by the DNA sequence method. In addition to this method, six men underwent CFTR analysis by a common 25 or 31 mutation panel coupled with poly T analysis. In 10 subjects, common mutation panel findings were inferred from DNA sequence method results.


RESULTS
Overall, 12/16 (75%) azoospermic patients had one or more CFTR mutations and/or 5T alleles, including 12 mutations in 10 patients (two compound heterozygotes) and seven 5T alleles in six patients (one homozygote). The sequence method detected all mutations and three variants of unknown significance. By comparison, the common mutation panels detected only 3/12 mutations (25%) and 0/3 variants.


CONCLUSIONS
The DNA sequence method detects more CFTR mutations than common mutation panels. Given the serious, clinical consequences of transmitting such mutations, this study underscores the importance of accurate, CFTR mutation detection in men with obstructive azoospermia and their partners.
Department of Urology, University of California San Francisco, 1600 Divisadero Street, Box 1695, San Francisco, CA 94143-1695, USA.
Kari L
KL
Danziger
Lauri D
LD
Black
Steven B
SB
Keiles
Anja
A
Kammesheidt
Paul J
PJ
Turek
D000483:Alleles; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D004247:DNA / Q000235:genetics*; D004252:DNA Mutational Analysis / Q000592:standards*; D005260:Female; D005787:Gene Frequency; D014644:Genetic Variation; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007248:Infertility, Male / Q000235:genetics*; D008297:Male; D009154:Mutation; D009845:Oligospermia / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D020539:Sequence Analysis, Protein; D014649:Vas Deferens / Q000002:abnormalities
C505032:CFTR protein, human; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D004247:DNA