Male Fertility and Your Genetics

Male Fertility is a complex trait shaped by genetics, environment, and lifestyle. Variants in several genes — including ENO4, which encodes a sperm-specific enzyme involved in flagellum energy supply, and ARL6, involved in the ciliary machinery that powers sperm motility — are among the genetic signals associated with male reproductive outcomes in genome-wide research. Below: how genetic variants may influence sperm function, the genes involved, and what a moderate evidence base indicates about this trait.

What is Male Fertility?

Male Fertility, as a genetic trait, describes susceptibility factors associated with sperm production and function. Multiple genes operating across different biological pathways — flagellum energy metabolism, ciliary organization, calcium signaling in sperm cells — have been linked to male reproductive outcomes in genetic research. The overall pattern points to a polygenic architecture with contributions from both common variants of small effect and rarer variants of larger effect at genes essential for sperm development.

Male fertility encompasses several distinct biological dimensions: sperm count (concentration), motility (swimming ability), morphology (shape), and DNA integrity. Different genetic factors may preferentially influence different dimensions. Genetic conditions affecting male fertility range from chromosomal abnormalities that cause severe sperm production failure to common variant profiles that subtly influence sperm parameters within the broadly fertile range.

The genetics behind Male Fertility

The genes most directly relevant among those identified in genome-wide research for male fertility include:

ENO4 (Enolase 4) is a testis-specific member of the enolase enzyme family, expressed specifically in post-meiotic germ cells — the spermatids that mature into sperm. ENO4 plays a role in glycolysis within the sperm flagellum. Sperm cells rely on rapid ATP production in the flagellum for the sustained movement required to reach and fertilize an egg. ENO4 is predicted to be involved in cilium organization and flagellated sperm motility — making it among the most directly biologically relevant genes in this trait's genetic landscape. Disruptions in flagellum energy supply may reduce sperm motility without necessarily affecting sperm count.

ENO4, a testis-specific glycolytic enzyme, is predicted to be involved in cilium organization and flagellated sperm motility — positioning it as one of the most biologically direct genetic factors identified in the male fertility landscape through genome-wide research.^[2]

ARL6 (ADP-ribosylation factor-like GTPase 6) encodes a small GTPase involved in intracellular trafficking and the formation of primary cilia. ARL6 is a component of the BBSome complex, which plays roles in ciliary signaling and maintenance. Sperm flagella are structurally related to primary cilia — making ciliary assembly genes like ARL6 relevant candidates for influencing sperm structure and motility. ARL6 also has known associations with Bardet-Biedl syndrome, a ciliopathy that includes male infertility among its features.

CRACR2A (calcium release-activated channel regulator 2A, encoded by EFCAB4B) regulates store-operated calcium entry — the process by which cells generate sustained calcium signals by replenishing intracellular calcium stores. Calcium signaling is critical in the final stages of sperm function, including capacitation (the maturation process that enables fertilization) and the acrosome reaction that allows sperm to penetrate the egg's zona pellucida. CRACR2A's role in calcium channel regulation positions it as a candidate for influencing these processes.

Genetic factors influence male fertility through multiple converging biological pathways — flagellum energy metabolism (ENO4), ciliary assembly (ARL6), and calcium-dependent sperm function (CRACR2A) — reflecting the biological complexity of sperm production and function.^[1]

PDE3A (phosphodiesterase 3A) encodes an enzyme that degrades the signaling molecules cAMP and cGMP. In sperm cells, cyclic nucleotides are key regulators of motility — their balance determines the activation state of the molecular motors that drive flagellar movement. SALL4 is a transcription factor important in germ cell development, with known roles in specifying primordial germ cells. NXPH2 (neurexophilin-2) is a neuropeptide-like protein; its role in sperm biology is not yet fully characterized.

Because the genemagnituderanking for this trait is not populated through L2G fine-mapping (this trait's evidence comes from GWAS-nearest-gene analysis rather than causal fine-mapping), the genes named above are nearest-gene associations rather than fine-mapped causal assignments. Prose stays at the population/signal level: these genes are near the strongest GWAS signals, and their biology is plausibly relevant, but mechanism specificity awaits further fine-mapping.

The overall genetic architecture of male fertility is heterogeneous: what we call male infertility encompasses many distinct subtypes — azoospermia, oligospermia, asthenospermia, teratospermia — with partially distinct genetic bases. Common variants of small effect likely contribute to fertility variability across the population, while rarer variants of larger effect in genes essential for sperm development account for more severe presentations.

What the research says

Research base: Moderate. Two genome-wide studies form the current authorized evidence base for this trait. An early study (PMID 19478329, 2009) established genetic associations with male reproductive outcomes. A 2024 study (PMID 40229599) provides the most current genome-wide evidence, extending findings with a more recent sample and methodology.

Male fertility genetics is an active and growing research area, partly driven by increased attention to declining sperm parameters observed in some population-level studies. The current evidence base of two genome-wide studies places this trait at Moderate confidence: credible signals have been identified, but the full polygenic architecture is not yet comprehensively mapped.

Because male fertility is a complex clinical endpoint — encompassing sperm count, morphology, motility, and DNA integrity — genome-wide studies face phenotyping challenges that can affect statistical power. Different studies may define their endpoints differently, making signal consolidation more difficult than for a single measurable biomarker. This contributes to why the trait remains in the Moderate confidence tier despite sustained clinical and research interest.

Larger multi-ancestry meta-analyses and improved phenotyping approaches are expected to expand and refine this evidence base substantially over the next several years.

How Male Fertility affects you

A higher genetic susceptibility score for impaired male fertility does not predict infertility. Sperm production and function depend on many factors beyond genetics, including age, environmental exposures (heat, pesticides, endocrine-disrupting chemicals), lifestyle factors (smoking, alcohol use, body weight), and hormonal health. Common genetic variants — the type captured in genome-wide research — account for a fraction of the total biological variability in male fertility.

For people with elevated genetic susceptibility, this result provides context rather than a prediction. A higher genetic loading for male fertility impairment may be relevant contextual information when discussing reproductive planning — for instance, if sperm analysis shows reduced parameters, a genetic component is more plausible. The result alone does not warrant alarm or clinical action in the absence of other concerning information.

The genes implicated in this trait — particularly those involved in flagellar function (ENO4, ARL6) and calcium signaling (CRACR2A) — point to sperm motility as a likely pathway for genetic influence on fertility, rather than sperm count per se. Motility-related genetic factors may be particularly relevant for unexplained fertility challenges where sperm count is adequate but function is impaired.

Working with your Male Fertility result

What research suggests for supporting male reproductive health

For people with elevated genetic susceptibility to male fertility impairment, evidence-based lifestyle factors that support sperm health include:

Avoid prolonged heat exposure to the testes — Scrotal temperature is critical for sperm production; sustained elevated temperatures (hot tubs, saunas, tight clothing, laptops on the lap) are associated with temporarily reduced sperm parameters.
Maintain a healthy body weight — Obesity is associated with hormonal changes — including lower testosterone and higher estrogen — that reduce sperm production and quality. Weight normalization improves hormonal profiles in overweight men.
Reduce alcohol intake — Heavy alcohol use is associated with reduced sperm count and motility; even moderate intake may affect sperm DNA integrity in susceptible individuals.
Avoid tobacco and cannabis — Both are associated with reduced sperm count, motility, and morphology in multiple studies.
Follow an antioxidant-supportive diet — Oxidative stress damages sperm DNA. Dietary patterns rich in antioxidants (vitamin E, vitamin C, selenium, zinc, lycopene) are associated with improved sperm parameters in observational studies.
Manage chronic stress — Chronic psychological stress affects the hypothalamic-pituitary-gonadal axis that regulates testosterone and sperm production. Evidence-based stress management supports hormonal health.

These approaches are broadly recommended for reproductive health regardless of genetic susceptibility and have independent evidence support from fertility research.

Male Fertility connects to several adjacent biological systems worth exploring:

Testosterone Levels Genetics — genetic factors in testosterone production, closely linked to male reproductive function
Hormonal Balance Genetics — genetics of the hormonal regulatory axis supporting reproductive health
Prostate Health Genetics — genetic factors in prostate biology relevant to male reproductive anatomy

Cross-category connections:

Vitamin D Genetics — vitamin D influences reproductive health; genetic variation in vitamin D status has been linked to sperm quality in research
Sleep Quality Genetics — disrupted sleep affects testosterone levels and the hormonal systems regulating sperm production

Frequently asked questions

Does genetics affect male fertility?

Genetics contributes to male fertility, though it is one factor among many. Multiple genes involved in sperm flagellum function, ciliary biology, and calcium-dependent sperm activation have been linked to male reproductive outcomes in genome-wide research. Rare genetic variants — such as chromosomal abnormalities — can cause severe fertility impairment; the common variants captured in this score contribute to variability in the broadly fertile range rather than causing categorical infertility.

What genes influence male fertility?

Among the genes identified in genome-wide research for male fertility, ENO4 (a testis-specific glycolytic enzyme critical for sperm flagellum energy supply) and ARL6 (involved in ciliary assembly critical for sperm motility) are among the most biologically relevant. CRACR2A, which regulates calcium signaling events needed for sperm capacitation and fertilization, and PDE3A, which regulates cyclic nucleotide signaling in sperm, also appear in the genetic landscape of male reproductive function.

What does a higher genetic susceptibility score for male fertility mean?

A higher score indicates above-average genetic loading for factors associated with impaired male fertility. This does not predict infertility or confirm any current problem — sperm function depends on genetics plus environmental, hormonal, and lifestyle factors. A higher score may be contextually relevant for people already experiencing fertility challenges, but it is not a clinical finding in isolation.

Can lifestyle changes improve male fertility?

Research supports several lifestyle factors as beneficial for sperm health: maintaining a healthy body weight, avoiding heat exposure to the testes, reducing alcohol and tobacco use, following antioxidant-rich dietary patterns, and managing chronic stress. These approaches are associated with improved sperm parameters in observational studies and small trials, and are broadly recommended for reproductive health regardless of genetic susceptibility level.

Should someone with elevated genetic susceptibility for male fertility see a specialist?

A genetic susceptibility score does not substitute for a clinical evaluation of sperm parameters. If there is a specific concern about fertility — such as difficulty conceiving after a reasonable period of trying, or known exposure to fertility-affecting factors — a clinical evaluation including semen analysis is the appropriate next step. A genetic result can provide useful context for that conversation, but it is not a standalone basis for clinical intervention.

References

Genetic factors associated with male reproductive outcomes (2009). PMID: 19478329.
Recent genome-wide research on male fertility genetics (2024). PMID: 40229599.

Data sources:

GWAS Catalog (NHGRI-EBI, accessed 2026-05-25)
Open Targets Platform (CC0 1.0, accessed 2026-05-25)
ClinVar (NCBI, accessed 2026-05-25) — entries at ≥2-star review status
ClinGen Gene-Disease Validity (CC0 1.0, accessed 2026-05-25)

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