Successful outcomes of intracytoplasmic sperm injection-embryo transfer using ejaculated spermatozoa from two Chinese asthenoteratozoospermic brothers with a compound heterozygous FSIP2 mutation

Multiple morphological abnormalities of the sperm flagella (MMAF) is a characteristic form of severe asthenozoospermia and closely related to male infertility. However, it is not sure whether intracytoplasmic sperm injection (ICSI) allows MMAF patients reproductive success. The present study reported the first case of successful intracytoplasmic sperm injection-embryo transfer (ICSI-ET) in Chinese brothers with a novel compound heterozygous mutation of FSIP2 (fibrous sheath interacting protein 2), a newly identified MMAF-related genes. The proband and his brother were referred for MMAF because of their abnormal sperm flagellum. Through whole-exome sequencing in the genetic analyses of the proband, his brother and parents showed that the proband and his brother carry a novel compound heterozygous FSIP2 mutation (c.1750T>A and c.13600A>G), which will lead to abnormal expression of FSIP2 and loss of its function. Considering that these brothers had the MMAF phenotype, we recommended ICSI treatment. The successful outcome of ICSI indicated that a lose-function mutation of FSIP2 might not have any effect on ICSI, although the latest report showed a failed outcome of ICSI in a patient with FSIP2 mutation. This study provides new knowledge to understand the effect of MMAF caused by FSIP2 mutation on ICSI outcome.