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Methylthioadenosine phosphorylase (MTAP) deficiency screening in leukocytes (qualitative)

Published: August 9, 2026Updated: August 16, 2026

This test checks for mutations in the methylthioadenosine phosphorylase (MTAP) gene, which may be linked to certain blood disorders like Fanconi anemia.

Quick summary

["Early detection of genetic mutations that could affect blood health and development."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
101633-6
Short code
MT-RNR1 Mut Anl Bld/T
Synonyms
MT-RNR1 Mut Anl Bld/T
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms of blood disorders, a family history of Fanconi anemia or other genetic blood diseases, or if you’re undergoing genetic counseling. It’s also sometimes part of a broader genetic evaluation.

What to Expect Before the Test

You’ll have a simple blood draw, usually from a vein in your arm. No special preparation is needed, but inform your provider about any medications or supplements you’re taking.

What the Results Mean

If mutations are found, they may help explain why you or a family member has certain blood-related health concerns. Results can guide further testing or treatment planning.

Common Conditions Linked to MTAP Deficiency

MTAP mutations are associated with Fanconi anemia, a rare genetic disorder affecting blood cell production and increasing cancer risk. Other blood disorders or developmental issues may also be linked.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Identifying MTAP mutations helps confirm or rule out genetic conditions that can cause blood abnormalities, such as anemia, bone marrow failure, or an increased cancer risk. Early detection allows for targeted interventions and better management of symptoms.

Short name

MTAP Mutation Screening (Blood)

Frequently asked questions

What is Fanconi anemia?
Fanconi anemia is a rare genetic disorder that affects how your bones and blood cells develop. People with this condition may have low red blood cells, white blood cells, or platelets, increasing their risk of infections or bleeding. It can also lead to bone abnormalities or cancer over time.
This test specifically looks for genetic mutations in the MTAP gene, not general blood chemistry or cell counts. It’s part of genetic testing, not a standard lab panel.
No, this test requires a blood sample to analyze white blood cells for genetic mutations. Saliva tests are not used for this specific purpose.
What if my test results are positive for MTAP mutations?
A positive result may indicate a higher risk for Fanconi anemia or related blood disorders. Your healthcare provider will discuss next steps, which may include additional genetic testing, monitoring, or genetic counseling.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy