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Sanfilippo syndrome (MPS III): Suspect-and-test checklist for clinicians

A one-page worksheet that turns the full Sanfilippo syndrome (MPS III) diagnosis guide into something you can use at the point of care: what to look for, what to order, which results should not end the workup, and who else to test or refer.

Who it is forClinicians and care teams who may see Sanfilippo syndrome (MPS III) before it is diagnosed, including primary care, the specialists named in the guide, and referral or genetics coordinators.
When to use itWhen Sanfilippo syndrome (MPS III) is on the differential, when a patient has several red flags, or when you are preparing a referral or a second opinion.

How to use it, section by section

  1. Red flags present: Tick each finding the patient has. They are grouped by body system so you can scan quickly.
  2. Already labeled as: Tick earlier diagnoses on the chart that the sources say are often given first.
  3. Family to test: Note relatives who may need testing, and record when symptoms began and which specialists have already been seen.
  4. Testing, in order: Tick each test as you order it and write the result on its line. The order follows the published sources.
  5. Results that do not rule it out: A reminder of findings that can look reassuring but do not exclude Sanfilippo syndrome (MPS III).
  6. Specialists: Tick the referral, then write who it went to and any notes.
Two ways to fill it inPrint it blank and write on it, or tick boxes and type on this screen first, then print or save as a PDF. Keep it with the chart or send it with the referral.
PrivacyNothing you type is sent or saved. It stays in this browser tab and disappears when you close it. Use patient initials, not full identifiers.

What it is not: Not a diagnostic score, a protocol or coding advice. It summarizes published sources, and clinical judgment and the treating clinician govern. Every point is sourced in the full Sanfilippo syndrome (MPS III) guide.

One Letter page. Use your browser's print or save as PDF.Full guide with sources
Suspect-and-test checklist
Sanfilippo syndrome (MPS III)

Recessive lysosomal disease, 4 subtypes. Looks like speech delay, autism or ADHD first. A normal urine GAG does not exclude it.

ICD-10-CME76.22Trial Friend for Clinicians

1Red flags present

Speech and development

Behavior and sleep

Ears, airway and gut

Appearance and abdomen

Older children and adults

Family

2Already labeled as

3Family to test

4Testing, in the order the sources describe

  1. Quantitative urine GAG, age-related rangeFirst morning or random sample. Spot tests are obsolete.
    Result
  2. GAG electrophoresis or heparan sulfate by MS/MSMS/MS is more sensitive and specific. No heparinized tubes.
    Result
  3. Enzyme panel, all 4 subtypes, leukocytes or fibroblastsGold standard; can be first line. Confirm a dried blood spot result.
    Result
  4. Second sulfataseWhen the type A or D enzyme is deficient, to rule out multiple sulfatase deficiency.
    Result
  5. SGSH, NAGLU, HGSNAT, GNS sequencing with deletion/duplicationNames the subtype and allows family testing. Confirm a molecular result biochemically.
    Result
  6. Exome or genome sequencingACMG 2021: consider first or second tier in developmental delay or intellectual disability.
    Result
  7. Confirm with 2 markersGAG accumulation, decreased enzyme activity, or pathogenic variants. Fayuvi is type A only.
    Result

5Results the sources say do not rule it out

  • Normal urine GAG. It cannot rule out MPS III, and dilute urine lowers sensitivity.
  • A normal face, liver and spleen.
  • An autism or ADHD diagnosis already made, even on formal testing.
  • A normal sponsored blood spot panel that does not list types A, C or D.

6Specialists the sources name

Diagnosis code: E76.22 Sanfilippo mucopolysaccharidosesCodes patients often carry before diagnosis are listed in the online guide.
Full guide and sourcesEvery point here is sourced in the online guide, which also has a patient note to print.
Trial Friend, trialfriend.com/for-clinicians. Key sources: GeneReviews (2019); Sanfilippo consensus guideline (2022); Wijburg 2013 misdiagnosis review; Kuiper 2018 Dutch diagnostic delay study; Buhrman 2014 Pittsburgh type A series; Delgadillo 2013 Spanish series; all 24 with links in the online guide. Checked November 11, 2026. A reference checklist for licensed clinicians that summarizes published sources. It is not a diagnostic tool, a score or a protocol, and it does not replace clinical judgment, local practice or the prescribing information. Not coding advice. Trial Friend never receives anything written or typed on this sheet.