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Background SPAG16 is a critical structural component of motile cilia and flagella. In the eukaryotic unicellular algae Chlamydomonas, loss of gene function causes flagellar paralysis and prevents assembly of the “9 + 2” axoneme central pair. In mice, we have previously shown that loss of Spag16 gene function causes male infertility and severe sperm motility defects. We have also reported that a heterozygous mutation of the human SPAG16 gene reduces stability of the sperm axonemal central apparatus.
Methods In the present study, we analyzed DNA samples from 60 infertile male volunteers of Western European (Italian) origin, to search for novel SPAG16 gene mutations, and to determine whether increased prevalence of SPAG16 single nucleotide polymorphisms (SNPs) was associated with infertility phenotypes. Semen parameters were evaluated by light microscopy and sperm morphology was comprehensively analyzed by transmission electron microscopy (TEM).
Results For gene analysis, sequences were generated covering exons encoding the conserved WD40 repeat region of the SPAG16 protein and the flanking splice junctions. No novel mutations were found, and the four SNPs in the assessed gene region were present at expected frequencies. The minor alleles were not associated with any assessed sperm parameter in the sample population.
Conclusions Analysis of the SPAG16 regions encoding the conserved WD repeats revealed no evidence for association of mutations or genetic variation with sperm motility and ultrastructural sperm characteristics in a cohort of Italian infertile males.
© 2012 Nagarkatti-Gude et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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VCU Obstetrics and Gynecology Publications
Table S1. Minor allele frequencies of all SNPs in the tested SPAG16 region. Expected minor allele frequencies refer to HapMap CEU European population  where available. Unknown = no data available for suitable reference population; * = Pilot 1 HapMap CEU panel, 60 individuals.
1471-2490-12-27-s2.pdf (27 kB)
Table S2. Tests for association between all SNPs in sample population and sperm phenotype. Association tests for each SNP found in the sample population and studied indicators of sperm structure and function. * = data assessed using arcsine of the square root of the phenotype; ^ = data assessed using log transformation of the phenotype; c = Bonferroni correction results in p > 0.1.