AB201. Sperm fluorescence in situ hybridization analysis of AZF cmicrodeletion in severe oligozoospermia

Objective: Microdeletions of azoospermia factor (AZF) regions in Y chromosome were a genetic risk factor of spermatogenic failure and male infertility. Most laboratories carried out the AZF microdeletion testing by using peripheral intravenous blood, and AZF microdeletion in spermatozoa of infertile patients was sometimes not identical to that of peripheral intravenous blood due to the existence of mosaicism. The aim of this study was to summarize the data of sperm fluorescence in situ hybridization (FISH) analysis of AZF microdeletion in patients with severe oligospermia.

Materials and methods: The experiment included 16 patients with severe oligospermia which didn’t find AZF microdeletions in peripheral intravenous blood. Additionally, 2 normozoospermic cases and 2 oligozoospermiccases with AZF microdeletion were recruited as positive controls and as negative controls respectively. Frequency of AZF microdeletion in spermatozoa was detected by FISH with probes for chromosomes Y and chromosome 18, SRY gene was selected as the Y chromosome-specific signal, DAZ gene as AZFc-specific signal. A total of 100 spermatozoa were observed in each group.

Results: A total of 2,000 spermatozoa were counted from the semen samples in three groups. The hybridization rate was 97.2%, 95.3% and 96.4% in experiment group, positive group and negative group respectively. five out of 16 patients with severe oligospermia was found to bear DAZ gene signal missing in sperms with SRY signal, and the average missing rate was 8.7%. The positive control group was not found signal missing of DAZ gene in sperms with SRY signal, and DAZ gene signal was not found in the negative control group

Conclusions: AZF microdeletions were not found in some patients with severe oligospermia via testing the peripheral intravenous blood, but sperm analysis by FISH revealed the presence of 8.7% abnormal spermatozoa with Y chromosome signal, in which DAZ gene signal were not found. This study is important to explain the mechanism of non-vertical transmission in patients with Y chromosome microdeletions, and can help to assess the genetic risk of Y chromosome microdeletions for male offspring and can be used for appropriate genetic counseling before the employment of assisted reproduction techniques.

Keywords: Severe oligospermia; sperm; fluorescence in situ hybridization (FISH); azoospermia factor (AZF)