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Updated: Apr 16, 2026
Mouse Round Spermatid Injection
Published on: January 26, 2024
RHOXF2 gene, a new candidate gene for spermatogenesis failure
Christophe Frainais1, Caroline Kannengiesser2, Martine Albert3
1Laboratoire Clement, Le Blanc Mesnil, F-93110 France.
Introduction:
Genes involved in testicular differentiation, spermatogenesis, proliferation and apoptosis of germ cells have been shown to evolve rapidly and display rapid DNA changes. These genes are therefore good candidates for explaining impairments in spermatogenesis. Initial studies of some of these genes appear to confirm this hypothesis. The RHOXF2 candidate gene belongs to the RHOX family clustered in Xq24 and is specifically expressed in the testis. It contains four exons and codes for a 288 amino acid (aa) transcription factor. It has a high degree of homology (>99.9%) with its paralogue RHOXF2B, which is also preferentially expressed in the testis.
Objectives:
To sequence RHOXF2 and RHOXF2B in intracytoplasmic sperm injection (ICSI) patients and identify any single-nucleotide polymorphisms (SNPs) associated with impaired spermatogenesis.
Materials:
A cohort of 327 patients in ICSI programmes at Poissy and Bichat hospitals. All patients gave their written, informed consent to participation. One hundred patients had unaffected spermatogenesis and 227 displayed impaired spermatogenesis.
Methods:
The four exons in each of RHOXF2 and RHOXF2B were sequenced in 47 patients with oligospermia or non-obstructive azoospermia. Given that exons 2 and 3 were found to harbour most of the SNPs, only these two exons were sequenced in the remaining 280 subjects.
Results:
Due to the extremely high degree of sequence identity between RHOXF2 and RHOXF2B, we were not able to distinguish between the sequences of these two genes. Although 9 SNPs were identified, there were no significant frequency differences between ICSI patients with normal vs. impaired spermatogenesis. Two insertions were identified: a 21-nucleotide insertion was retrieved in both groups and a guanine insertion (inducing a premature stop codon) only found in two patients with impaired spermatogenesis.
Conclusion/Outlook:
RHOXF2 is a good candidate for rapid evolution by positive selection. Analysis of the polymorphism frequency in exons 2 and 3 did not allow us to correlate the identified SNPs with male infertility. However, a single nucleotide insertion was identified only in men with impaired spermatogenesis. Further work will be needed to establish whether genetic changes in RHOXF2 can give rise to defects in spermatogenesis.
Insights
Rapidly evolving genes like RHOXF2 are linked to spermatogenesis. Sequencing RHOXF2 and RHOXF2B in intracytoplasmic sperm injection (ICSI) patients found no significant SNP differences, but identified a guanine insertion in infertile men.
Area of Science:
- Genetics
- Reproductive Biology
- Molecular Evolution
Background:
- Genes regulating germ cell development evolve rapidly, making them candidates for spermatogenesis impairments.
- RHOXF2, a testis-specific gene on chromosome Xq24, is highly homologous to RHOXF2B.
Purpose of the Study:
- To sequence RHOXF2 and RHOXF2B in patients undergoing intracytoplasmic sperm injection (ICSI).
- To identify single-nucleotide polymorphisms (SNPs) associated with impaired spermatogenesis.
Main Methods:
- Sequencing of RHOXF2 and RHOXF2B exons in 327 ICSI patients (100 with normal, 227 with impaired spermatogenesis).
- Initial sequencing of all four exons in 47 patients, followed by sequencing of exons 2 and 3 in the remaining 280 patients due to high SNP frequency in these regions.
Main Results:
- High sequence identity between RHOXF2 and RHOXF2B precluded distinguishing between them.
- Nine SNPs were identified, but no significant frequency differences were observed between patients with normal and impaired spermatogenesis.
- A 21-nucleotide insertion was found in both groups, while a guanine insertion, causing a premature stop codon, was exclusively identified in two patients with impaired spermatogenesis.
Conclusions:
- RHOXF2 exhibits characteristics of rapid evolution, potentially influenced by positive selection.
- Identified SNPs in RHOXF2 exons 2 and 3 were not correlated with male infertility.
- A specific guanine insertion in RHOXF2 may be linked to impaired spermatogenesis, warranting further investigation into RHOXF2's role in male fertility.
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