[Molecular analysis of protein 4.1 gene in teratozoospermic and azoospermic patients]

In normal sperm, the 135 kD isoform of protein 4.1 is replaced by the 80 kD variant. Transcript for protein 4.1 loses the 'upstream' initiation codon by a stage-dependent alternative splicing and in mature sperm only 'downstream' initiation codon is active. A mutation in the 'downstream' initiation codon may be a reason for sperm differentiation arrest (azoospermia) or can be associated with the presence of amorphous spermatozoa in ejaculate (teratozoospermia). The aim of the study was the molecular analysis of gene coding for the protein 4.1, carrying a 'downstream' translation initiation codon. We have screened DNA samples obtained from azoospermic (blood) and teratozoospermic (spermatozoa) patients using PCR amplification of gene fragment, AUG containing exon with subsequent digestion (NlaIII) of CATG sequence. The absence of a cleavage site for this restriction enzyme would suggest the presence of mutation in the AUG codon. Analysis of DNA samples obtained from both azoospermic and teratozoospermic patients did not reveal any changes in the 'downstream' translation initiation codon. We concluded therefore that observed by others a defective expression of protein 4.1 in amorphous sperm cells is probably due to the other factor(s) than mutation in the 'downstream' translation initiation codon.