SPATA16 rs35033974: Understanding Reproductive Genetic Variants
The rs35033974 variant is a rare genetic change located within the SPATA16 gene. It is associated with a condition known as globozoospermia, which affects sperm morphology and can lead to male factor infertility.
What each genotype means
Typical SPATA16 genotype
This is the most common genotype for this variant. It is not associated with the specific loss-of-function mutations in SPATA16 that have been linked to globozoospermia and male infertility.
This genotype is found in the vast majority of the global population.
Heterozygous carrier status
You carry one copy of the variant allele. Because SPATA16-related globozoospermia typically follows an autosomal recessive inheritance pattern, carrying a single copy is generally not considered sufficient to cause the condition.
This genotype is extremely rare, consistent with the global allele frequency of less than 0.00005.
Potential reproductive risk
This genotype represents the homozygous state for the variant. Research has linked homozygous mutations in SPATA16 to globozoospermia, a condition where sperm lack an acrosome, leading to primary male factor infertility. Please discuss these findings with a reproductive specialist or genetic counselor to understand their clinical relevance to your health.
This genotype is exceptionally rare in the general population.
What is the rs35033974 Variant?
The rs35033974 variant is a specific change in the DNA sequence of the SPATA16 gene. In genetics, a single nucleotide polymorphism (SNP) like this represents a variation at a single position in the genome. This particular variant is categorized as a missense mutation, meaning it results in a change to the amino acid sequence of the protein produced by the gene. Because the SPATA16 gene is critical for the development of healthy sperm, changes in its sequence can potentially disrupt normal biological processes. Researchers track these variants to understand how they influence human health, particularly in the context of reproductive biology. It is important to note that the presence of a variant does not automatically imply a clinical diagnosis, as genetic expression is complex and influenced by many factors.
The Role of the SPATA16 Gene
The SPATA16 gene, which stands for Spermatogenesis Associated 16, plays a vital role in the male reproductive system. It encodes a protein that is primarily expressed in the testes and is essential for the formation of the acrosome. The acrosome is a specialized cap-like structure on the head of a sperm cell that contains enzymes necessary for penetrating the outer membrane of an egg. During the process of spermatogenesis, the SPATA16 protein helps facilitate the transport of Golgi-derived vesicles that form this critical structure. When the SPATA16 gene is disrupted, the resulting sperm may lack an acrosome and exhibit a round-headed shape, a condition known as globozoospermia. This structural defect prevents the sperm from successfully fertilizing an egg, which is a recognized cause of primary male factor infertility.
Research and Evidence Strength
Current scientific literature identifies SPATA16 as a key gene involved in the pathogenesis of globozoospermia. Research has linked loss-of-function mutations in this gene to the failure of acrosome biogenesis. However, the evidence strength for the specific rs35033974 variant is currently considered limited. While the gene itself is well-characterized in the context of reproductive health, clinical data regarding this specific variant is still evolving. Scientific studies often use techniques like next-generation sequencing to identify these variants in patients experiencing infertility. Because reproductive health is influenced by a wide array of genetic and environmental factors, researchers emphasize that identifying a variant is only one piece of a much larger puzzle. Further studies are required to fully understand the penetrance and clinical impact of this specific variant across diverse populations.
Population Frequency
The rs35033974 variant is extremely rare in the general population. According to data from the Genome Aggregation Database (gnomAD), the global allele frequency for this variant is less than 0.00005. This low frequency indicates that the variant is not commonly found in the general public, which is consistent with its association with a rare, specific reproductive condition. Because it is so uncommon, large-scale population studies have limited data on how it manifests across different ancestral groups. Geneticists use these population databases to distinguish between common variations that are part of normal human diversity and rare variants that may have significant clinical implications. The rarity of this variant underscores the importance of clinical genetic counseling for individuals who may be investigating the underlying causes of fertility challenges.
Navigating Genetic Information
If you have received information about this variant, it is essential to understand what you can and cannot do with it. Genetic information is complex and should always be interpreted in the context of your personal medical history and clinical findings. You cannot use this information to self-diagnose or predict reproductive outcomes with certainty. If you are concerned about fertility, the most appropriate step is to consult with a reproductive endocrinologist, urologist, or a certified genetic counselor. These professionals can provide context, order appropriate clinical testing, and discuss potential assisted reproductive technologies (ART) if necessary. Never make medical decisions based solely on a genetic report. Always discuss your results with a qualified healthcare provider who can integrate your genetic data with physical examinations and other diagnostic tests to provide a comprehensive assessment of your health.
How common is this variant?
The rs35033974 variant is extremely rare, with a global allele frequency of less than 0.00005 in the gnomAD database.
Frequently asked questions
What is globozoospermia?
Globozoospermia is a rare condition where sperm cells have round heads and lack an acrosome. Because the acrosome is needed to penetrate an egg, this condition typically results in male infertility.
Does having this variant mean I am infertile?
Not necessarily. Genetic variants are only one factor in reproductive health, and clinical outcomes can vary. You should consult a fertility specialist to discuss your specific situation.
Can I fix this genetic variant?
Currently, there is no medical treatment to 'fix' or change a genetic variant in your DNA. However, individuals with fertility challenges can often explore assisted reproductive technologies with the help of a specialist.
Where can I get tested for this variant?
Clinical genetic testing is typically ordered by a healthcare provider, such as a urologist or reproductive specialist. They can ensure that the testing is appropriate and that the results are interpreted correctly.
Sources & further reading
Educational information only, last refreshed 9/17/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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A missense change in SPATA16 that impairs Golgi-derived acrosome vesicle transport, causing round-headed sperm morphology (globozoospermia) and fertilization failure.
Homozygous mutations in SPATA16 are a known cause of spermatogenic failure type 6 (SPGF6), characterized by globozoospermia and male infertility due to acrosome formation defects.