PAH rs199475612: What Your Genotype Means
The rs199475612 variant is a specific change located within the PAH gene. It is recognized in genetic databases as a carrier marker associated with phenylketonuria (PKU), an inherited metabolic condition.
What each genotype means
Typical PAH gene profile
This genotype represents the common, non-variant form of this specific location in the PAH gene. Individuals with this profile do not carry this specific marker associated with phenylketonuria (PKU) at this position.
This is the most common genotype observed in the general population.
Phenylketonuria mutation carrier
This genotype indicates you are a carrier of a variant associated with phenylketonuria (PKU). As PKU is an autosomal recessive condition, carriers are typically unaffected, but you should discuss this result with a genetic counselor or clinician to understand the implications for family planning.
This genotype is rare in the general population.
Potential phenylketonuria risk
This genotype indicates the presence of the variant on both copies of the PAH gene. Because this variant is linked to phenylketonuria, you should consult with a medical professional or metabolic specialist to discuss clinical testing and what this means for your health.
This genotype is extremely rare in the general population.
Understanding the SNP and Its Location
The variant rs199475612 is a single nucleotide polymorphism (SNP) situated on chromosome 12, which is the location of the PAH gene. In genetics, a SNP represents a variation at a single position in the DNA sequence among individuals. This specific variant is cataloged in public databases like dbSNP and SNPedia, which track variations across the human genome. Because it is located within the PAH gene, researchers monitor it to determine if it alters the gene's function or the protein it produces. Understanding the precise location of a variant helps scientists study how it might influence biological processes, though not all SNPs have a measurable impact on health. This variant is specifically noted for its potential role in carrier status for certain metabolic conditions.
The Role of the PAH Gene
The PAH gene provides the essential instructions for the body to create an enzyme called phenylalanine hydroxylase. This enzyme plays a critical role in the metabolism of phenylalanine, an amino acid found in many protein-rich foods. Under normal conditions, phenylalanine hydroxylase converts phenylalanine into another amino acid called tyrosine. When the PAH gene contains certain variants that reduce or eliminate the activity of this enzyme, phenylalanine can build up to toxic levels in the blood and brain. This accumulation is the underlying cause of phenylketonuria (PKU). Because the body relies on this enzyme to maintain healthy amino acid levels, the functional integrity of the PAH gene is vital for normal metabolic health.
Research and Evidence Strength
Current research classifies rs199475612 as a carrier marker for phenylketonuria. PKU is an autosomal recessive condition, meaning that an individual typically needs to inherit two copies of a pathogenic variant—one from each parent—to manifest the clinical symptoms of the disorder. As a carrier, an individual possesses one copy of the variant and one functional copy of the gene, which is generally sufficient to maintain normal enzyme activity and prevent the condition. The evidence strength for this variant's association with carrier status is considered moderate. While it is identified in clinical databases, the clinical significance of any single variant can be complex, as the severity of PKU depends on the specific combination of variants inherited. Genetic testing results should always be interpreted by a qualified healthcare professional or genetic counselor.
Population Frequency
The rs199475612 variant is classified as rare in the general population. Because it is a rare variant, it is not commonly found in large-scale genomic studies of the general public. Its frequency can vary significantly depending on ancestral background, as certain genetic variants are more prevalent in specific geographic or ethnic groups due to historical population patterns. Because the variant is rare, most individuals will not carry it. If you have received a report indicating you are a carrier, it simply means you have one copy of this specific genetic change. It does not mean you have the condition itself, but it is information that can be relevant for family planning and understanding your genetic profile.
What You Can and Cannot Do With This Information
Knowing your status for rs199475612 provides insight into your genetic makeup, but it is not a medical diagnosis. If you are identified as a carrier, you are generally unaffected by the condition. However, this information is useful for understanding your carrier status, which may be relevant if you are planning a family, as your partner's genetic status would also be a factor in the likelihood of passing on a condition. You cannot use this information to diagnose yourself or others, nor should it be used to make changes to your diet or medical care without consulting a doctor. Always discuss genetic findings with a healthcare provider or a certified genetic counselor who can provide context based on your personal and family medical history.
How common is this variant?
This variant is considered rare across global populations, meaning it is not frequently observed in the general public.
Frequently asked questions
What does it mean to be a carrier for PKU?
Being a carrier means you have one copy of a gene variant associated with PKU, but you do not have the condition yourself. Because PKU is recessive, you would typically need two copies of a pathogenic variant to show symptoms.
Should I change my diet if I am a carrier?
No, carriers of PKU variants do not need to follow a special diet. The condition only affects individuals who have two pathogenic variants that significantly impair the PAH enzyme's function.
How do I know if my partner is a carrier?
The only way to know if your partner is a carrier is through genetic testing. If you are concerned about family planning, you should speak with a genetic counselor who can explain the risks and testing options.
Is this variant the only cause of PKU?
No, there are over 1,000 different variants in the PAH gene that can contribute to PKU. This variant is just one of many that researchers have identified.
Sources & further reading
Educational information only, last refreshed 9/30/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This variant is associated with carrier status for phenylketonuria, a metabolic disorder.
This variant is associated with carrier status for phenylketonuria, a metabolic disorder.
This variant is considered probably pathogenic and is associated with phenylketonuria carrier status.
This variant is associated with carrier status for phenylketonuria, a metabolic disorder.
A missense variant (c.1222C>T, p.Arg408Trp) that disrupts phenylalanine hydroxylase activity, defining carrier status for classic autosomal recessive phenylketonuria across Eastern and Northern Europe.
A splice-donor site variant (c.1066-11G>A, legacy IVS10nt-11) causing phenylalanine hydroxylase deficiency and serving as a frequent carrier screening marker for phenylketonuria.