Hypo-osmotic swelling test guided sperm selection followed by intracytoplasmic sperm injection in two men with multiple morphological abnormalities of the sperm flagella associated with SPEF2 and CFAP251 variants: two case reports.

BACKGROUND: Multiple morphological abnormalities of the sperm flagella (MMAF) is a rare but severe form of asthenozoospermia. It is characterized by multiple abnormalities in sperm flagella, manifesting as various combinations of short, absent, coiled, curved, and/or irregularly diameter flagella. For MMAF patients with no motile sperm in their semen, it is necessary to identify viable immotile sperm for assisted conception via intracytoplasmic sperm injection (ICSI). The hypo-osmotic swelling test (HOST) technique is one method used to identify viable immotile sperm.

CASE DESCRIPTION: Both patients were young men diagnosed with MMAF and had no motile sperm in their semen. Genetic testing revealed a sperm flagellar 2 (SPEF2) gene mutation in patient A and a cilia and flagella associated protein 251 (CFAP251) gene mutation in patient B. Live immotile sperm were successfully identified in both patients using the HOST, and ICSI was performed. They underwent ICSI successfully and achieved pregnancy. Both couples achieved live births following ICSI treatment.

CONCLUSIONS: For MMAF patients lacking motile sperm, the HOST is a viable method for identifying viable sperm for ICSI. These two cases, caused by SPEF2 and CFAP251 mutations, provide clinical evidence supporting the potential for successful assisted conception via ICSI in MMAF patients with different genetic etiologies.