Globozoospermia is associated with chromatin structure abnormalities

Abstract

A recent study has shown normal sperm chromatin structure in a patient with globozoospermia. However, the poor success rate following intracytoplasmic sperm injection (ICSI) with the use of this sperm suggests that sperm nuclear abnormalities may be present. We report here a study of the sperm DNA integrity and chromosome aneuploidy and diploidy rates of a patient with 100% round-headed sperm. The sperm chromatin packaging quality was assessed by using flow cytometry after staining the DNA with propidium iodide. DNA fragmentation, possibly indicative of apoptosis, was evaluated by flow cytometry using the terminal deoxynucleotidyl transferase-mediated fluorescein-dUTP nick-end labelling (TUNEL) assay. The sperm chromosome aneuploidy and diploidy rates were evaluated by fluorescence in-situ hybridization using α-centromeric probes for chromosomes 8, 12, 18, X and Y. The patient with globozoospermia had a significantly higher number of sperm with chromatin decondensation (35 ± 1.1%) and positive for the TUNEL assay (37 ± 1.7%) compared with that found in four normal controls (4.7 ± 0.4 and 22.5 ± 1.2% respectively). In contrast, the total sperm aneuploidy (0.16%) and diploidy (0.05%) rates for the chromosomes studied were within the range found in 14 normozoospermic men. To the best of our knowledge, this is the first case report of round-headed sperm that has shown an elevated number of sperm with abnormal chromatin structure and DNA strand breaks.