Editing Infertility: Diagnosis and Evaluation (section)

=== Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) mutation carrier testing ===

* '''Including assessment of the 5T allele'''
** In addition to classic mutations, the 5-thymidine (5T) variant of the polythymidine tract in the splice site of intron 8 (which regulates exon 9 splicing efficiency) is also commonly found in men with obstructive azoospermia due to ''CFTR'' abnormalities. 
*'''For men who harbor a ''CFTR'' mutation, genetic evaluation of the female partner should be recommended.'''
** In cases where the male patient has a mutation in the ''CFTR'' gene and the partner is also a carrier, then there is a risk of an affected offspring (25% if both partners are carriers, and up to 50% if the male has mutations in both alleles with a female partner who is a carrier)

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