AR Gene rs121908755: Understanding Androgen Receptor Variants
The rs121908755 variant is a rare genetic change located within the AR gene, which provides instructions for making the androgen receptor protein. This specific variant is classified as pathogenic and is associated with androgen insensitivity syndrome, a condition affecting sexual development.
What each genotype means
Typical androgen receptor function
This genotype represents the typical sequence for the AR gene at this location. It is associated with normal androgen receptor function and does not contribute to androgen insensitivity syndrome.
This is the most common genotype found in the general population.
Potential androgen receptor variant
This genotype includes one copy of the pathogenic variant associated with androgen insensitivity syndrome. Because the AR gene is located on the X chromosome, individuals with only one X chromosome (typically males) who carry this variant may experience symptoms of androgen resistance, while individuals with two X chromosomes (typically females) may be carriers.
This genotype is extremely rare and is generally absent from large-scale population databases like gnomAD.
Androgen receptor variant present
This genotype indicates the presence of the pathogenic variant on the X chromosome. In individuals with one X chromosome, this is associated with clinical features of androgen insensitivity syndrome or related androgen resistance conditions. Clinical consultation is recommended to understand the specific implications for health and development.
This genotype is extremely rare and is not observed in standard population frequency datasets.
What is the rs121908755 Variant?
The rs121908755 variant is a specific alteration in the DNA sequence of the AR gene. In genetics, a variant like this is often referred to as a missense mutation, meaning it causes a single building block of the protein—an amino acid—to be replaced by a different one. This change occurs within the androgen receptor gene, which is located on the X chromosome. Because the AR gene is responsible for creating a protein that allows cells to respond to male sex hormones, any significant change in its structure can disrupt how these hormones function in the body. This variant is categorized as pathogenic, indicating that it is known to interfere with the normal biological processes governed by the androgen receptor. It is a rare genetic finding that has been identified in clinical settings during the investigation of individuals with differences in sexual development.
The Role of the AR Gene
The AR gene encodes the androgen receptor, a protein that acts as a transcription factor. This means it helps control the activity of other genes by binding to DNA when activated by hormones like testosterone and dihydrotestosterone. The androgen receptor is essential for normal male sexual development before birth and during puberty. It is expressed in many tissues throughout the body, including the prostate, hair follicles, and muscle. When the receptor functions correctly, it allows the body to respond to androgens, which drive the development of male physical characteristics. If the AR gene contains a mutation that prevents the receptor from working properly, the body may not respond to these hormones, even if they are present at normal levels. This lack of response is the underlying cause of androgen insensitivity syndrome, a condition that can present with a wide range of physical features depending on the severity of the receptor's dysfunction.
Clinical Associations and Evidence
Research associates the rs121908755 variant with androgen insensitivity syndrome (AIS). AIS is an X-linked recessive condition, meaning it primarily affects individuals with an XY chromosome pair. The clinical spectrum of AIS is broad, ranging from complete androgen insensitivity (CAIS), where the body does not respond to androgens at all, to partial (PAIS) or mild (MAIS) forms. In cases of CAIS, individuals typically have external female sex characteristics but do not have a uterus and have undescended testes. The evidence linking pathogenic variants in the AR gene to these conditions is considered strong in clinical genetics. However, because AIS is a complex condition, the presence of a variant does not always predict the exact clinical outcome for every individual. Clinical diagnosis is typically confirmed through a combination of physical examination, hormone level testing, and genetic sequencing to identify the specific mutation within the AR gene.
Population Frequency and Interpretation
The rs121908755 variant is extremely rare in the general population. According to large-scale genomic databases like gnomAD, this specific variant is absent from standard exome sequencing datasets. Its rarity means that it is not a common polymorphism found in the general public, but rather a specific clinical finding often identified in individuals undergoing genetic testing for disorders of sex development. Because it is so rare, there is limited data on its frequency across different ancestral groups. For individuals who receive information about this variant, it is important to understand that genetic testing results should always be interpreted by a qualified healthcare professional, such as a genetic counselor or a medical geneticist. They can provide context based on an individual's personal and family medical history. This information is for educational purposes and should not be used to make personal health decisions or diagnoses without professional clinical guidance.
How common is this variant?
The rs121908755 variant is extremely rare and is currently absent from major population databases like gnomAD.
Frequently asked questions
What is androgen insensitivity syndrome?
Androgen insensitivity syndrome is a genetic condition that prevents the body from responding to male sex hormones. This can lead to a range of physical characteristics, from typical female features to ambiguous genitalia or impaired male development.
Is rs121908755 a common genetic variant?
No, this variant is extremely rare. It is not found in the general population and is typically only identified in clinical settings during specialized genetic testing.
How is this variant inherited?
The AR gene is located on the X chromosome, and the condition follows an X-linked recessive pattern. This means it is often passed from a mother to her children, though it can also occur as a new, de novo mutation.
What should I do if I have this variant?
If you have received a report identifying this variant, you should discuss the results with a medical geneticist or a specialist in reproductive health. They can help you understand what this means for your health and provide appropriate clinical guidance.
Sources & further reading
Educational information only, last refreshed 9/22/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Intronic variant at the androgen receptor locus associated with hereditary male pattern baldness.
This variant in the androgen receptor gene is associated with androgen insensitivity and has been linked to variations in human adult height.
Pathogenic substitution in the androgen receptor gene leading to partial or complete androgen insensitivity syndrome and male infertility.
Androgen receptor variant associated with male-pattern (androgenetic) hair loss.
Point mutation in AR causing mild androgen insensitivity syndrome, presenting with impaired spermatogenesis and male infertility.