Analysis of copy number variation (CNV) of the SPANXA-E gene family in infertile and fertile men

Abstract

OBJECTIVE: The purpose of this study was to evaluate the role of copy number variation (CNVs) in male infertility by genotyping a candidate gene family, SPANXA-E, on the X chromosome in fertile and infertile men.DESIGN: An assay was developed to measure copy number variation (CNV) of SPANXB and its surrounding gene cluster using quantitative real time PCR (qPCR). This assay was used to compare CNV values of 100 infertile men (50 oligozoospermic and 50 azoospermic) and 67 normospermic men.MATERIALS AND METHODS: Assay validation was achieved via comparison to oligonucleotide-based CNV data from a set of eight individuals. The qPCR correlation coefficient for copy number of the SPANXB and SPANXA-E assays were 0.96 and 0.89, respectively, suggesting high assay validity. Copy number (CN) was estimated from qPCR results by comparing values for test individuals to a normal (single copy) female reference.RESULTS: SPANXB. CN was calculated for 96 infertile males and 51 fertile men. The average value for the infertile group was .52 (.03-1.96), and 47 (.01-1.7) for the fertile group. These values are consistent with the expected value of .5 indicating one X in a male in comparison to a female with two X chromosomes. The azoospermic and oligozoospermic group reported an average mean of .51, and .44 respectively. SPANXA-E Gene Cluster. CN was calculated for 96 infertile males and 44 fertile men. The average value for the infertile group was .49 (.05-2.6), and .44 (.35-1.34) for the fertile group. These values are consistent with the expected value of .5 indicating one X in a male in comparison to a female with two X chromosomes. The azoospermic group reported an average mean of .5, and the oligozoospermic group reported an average mean of .46.CONCLUSIONS: Initial evidence suggests no difference in CNV of SPANXB and SPANXA-E in infertile men compared to fertile men. The average means of groups stratified by diagnosis showed no difference when compared to the control group. The observed variation of the SPANXA-E gene cluster in these men suggests no correlation of CN with fertility status. Although SPANXA-E CN does not appear to be associated with male infertility, this area of genetic analysis remains a focus for complex diseases, such as male infertility, and further genome-wide CN analysis is warranted. OBJECTIVE: The purpose of this study was to evaluate the role of copy number variation (CNVs) in male infertility by genotyping a candidate gene family, SPANXA-E, on the X chromosome in fertile and infertile men. DESIGN: An assay was developed to measure copy number variation (CNV) of SPANXB and its surrounding gene cluster using quantitative real time PCR (qPCR). This assay was used to compare CNV values of 100 infertile men (50 oligozoospermic and 50 azoospermic) and 67 normospermic men. MATERIALS AND METHODS: Assay validation was achieved via comparison to oligonucleotide-based CNV data from a set of eight individuals. The qPCR correlation coefficient for copy number of the SPANXB and SPANXA-E assays were 0.96 and 0.89, respectively, suggesting high assay validity. Copy number (CN) was estimated from qPCR results by comparing values for test individuals to a normal (single copy) female reference. RESULTS: SPANXB. CN was calculated for 96 infertile males and 51 fertile men. The average value for the infertile group was .52 (.03-1.96), and 47 (.01-1.7) for the fertile group. These values are consistent with the expected value of .5 indicating one X in a male in comparison to a female with two X chromosomes. The azoospermic and oligozoospermic group reported an average mean of .51, and .44 respectively. SPANXA-E Gene Cluster. CN was calculated for 96 infertile males and 44 fertile men. The average value for the infertile group was .49 (.05-2.6), and .44 (.35-1.34) for the fertile group. These values are consistent with the expected value of .5 indicating one X in a male in comparison to a female with two X chromosomes. The azoospermic group reported an average mean of .5, and the oligozoospermic group reported an average mean of .46. CONCLUSIONS: Initial evidence suggests no difference in CNV of SPANXB and SPANXA-E in infertile men compared to fertile men. The average means of groups stratified by diagnosis showed no difference when compared to the control group. The observed variation of the SPANXA-E gene cluster in these men suggests no correlation of CN with fertility status. Although SPANXA-E CN does not appear to be associated with male infertility, this area of genetic analysis remains a focus for complex diseases, such as male infertility, and further genome-wide CN analysis is warranted.