RARE DISEASERESEARCH ATLAS
Open navigation menu

ORPHA:59

Allan-Herndon-Dudley syndrome

low confidenceDisorder

Also known as: AHDS · MCT8 deficiency · Monocarboxylate transporter 8 deficiency · X-linked intellectual disability-hypotonia syndrome

Publications

1,626

Trials

4

Interventional, condition-specific

Researchers

1,172

Distinct authors in sample

Gene link

SLC16A2

Definitive

Readiness

6/6

Stages with a signal

Clinical definition (Orphanet)

A rare X-linked syndromic with neuromuscular involvement characterized by a varying degree of neurodevelopmental delay including , hypokinesia, dystonia and spasticity, and a wide range of clinical sequelae secondary to chronic peripheral thyrotoxicosis.

How rare: How common this is has not been clearly measured.

Orphanet entry

Cross-references

Joined from Mondo / Orphanet. MeSH labels may enter searches; UMLS / OMIM / NCIT are stored for reference.

Additional Mondo synonyms (4)

ALLAN-Herndon syndrome · MCT8-Specific Thyroid Hormone Cell Transporter Deficiency · MCT8-specific thyroid hormone cell Membrane transporter deficiency · monocarboxylate transporter 8 deficiency

Research stages

Trial readiness signals

Where this condition sits on an open-data research pipeline — not how close a treatment is, and not medical advice. Empty stages often mean “not in these databases under this Mondo ID,” not “impossible.”

6/6 stages with a signal

An interventional trial matched this condition name on ClinicalTrials.gov — see trials below.

  1. Gene identifiedPresent

    Definitive — SLC16A2

  2. LiteraturePresent

    1,626 matched papers (1,144 in last 10 years) Source

  3. Phenotype characterisedPresent

    88 HPO annotations (e.g. Axial hypotonia; Narrow face; Pectus excavatum) Source

  4. Animal modelPresent

    4 genotype models (Mus musculus, Danio rerio) Source

  5. Orphan designationPresent

    2 FDA · 3 EMA designations (2 FDA orphan-indication approvals) — e.g. 3,5-diiodothyropropionic acid Source

  6. Interventional trialPresent

    4 matched on ClinicalTrials.gov

Biology

Genes and phenotypes

Gene–disease validity from GenCC, plus phenotypes and animal models joined from Monarch Initiative via Mondo ID — not a clinical diagnosis aid.

Do we know what causes it?

Yes — we know a specific gene responsible (SLC16A2).

GenCC classification: Definitive.

Phenotypes (Monarch / HPO)

88

Associated phenotypes · MONDO:0010354

  • Axial hypotonia
  • Narrow face
  • Pectus excavatum
  • Pes planus
  • Myopathic facies

Showing 5 of 88 — open Monarch for the full list.

Animal models (Monarch / Alliance)

4

Model associations linked to this Mondo ID

Monarch fetch 2026-07-29

Therapies

Designations, candidates, and chemicals

FDA OOPD and EMA orphan designations, Open Targets clinical candidates, and CTD chemical associations via MyDisease.info. These never change the interventional-trial headline.

Orphan designation (FDA · EMA)

5

Designations · 2 with FDA orphan-indication approval

  • FDA 3,5-diiodothyropropionic acidAllan-Herndon-Dudley syndrome · 2020-07-28 · Not FDA Approved for Orphan Indication
  • FDA 3,5-diiodothyropropionic acidAllan-Herndon-Dudley syndrome · 2013-05-14 · Not FDA Approved for Orphan Indication
  • EMA 3,5-diiodothyropropionic acidTreatment of Allan-Herndon-Dudley syndrome · 19/07/2021 · PositiveEMA designation
  • EMA tiratricol (Emcitate)Treatment of Allan-Herndon-Dudley syndrome · 12/10/2017 · PositiveEMA designation
  • EMA 3,5-diiodothyropropionic acidTreatment of Allan-Herndon-Dudley syndrome · 07/10/2013 · PositiveEMA designation

Sources: FDA OOPD · EMA orphan designations

Open Targets candidates

2

Drugs / clinical candidates · MONDO_0010354

CTD chemicals (MyDisease.info)

No CTD chemical associations returned for this Mondo ID.

Literature

Is anyone studying this?

1,626

1,626 papers have been published on this condition. That is a real research literature — still far smaller than common diseases (breast cancer: over 700,000 papers). Median papers in the last 10 years for a rare disease in this dataset (publications denominator n=3967) is 59.

1,626 papers since the earliest indexed year in this search — median last-10-year count for a rare disease in this dataset is 59 (publications denominator n=3967).

1,144 in the last 10 years · low confidence

Phrase hits: 688 · MeSH hits: 0

Open Europe PMC search

Who's working on it?

1,172

Distinct author names in 200 sampled papers — named people below.

Who's working on it?

People publishing on this condition (sampled Europe PMC records). Affiliation is the most recent found in that sample.

  1. 01
    Visser WE21 papers · 2026

    Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.

    Papers in Europe PMC
  2. 02
    Heuer H20 papers · 2026

    Department of Endocrinology, University of Duisburg-Essen, University Hospital Essen, D-45147 Essen, Germany.

    Papers in Europe PMC
  3. 03
    Groeneweg S14 papers · 2025

    Department of Internal Medicine, Erasmus Medical Center, Academic Center for Thyroid Diseases, Rotterdam, The Netherlands.

    Papers in Europe PMC
  4. 04
    Mayerl S12 papers · 2026

    Department of Endocrinology, University of Duisburg-Essen, University Hospital Essen, D-45147 Essen, Germany.

    Papers in Europe PMC
  5. 05
    Krude H11 papers · 2025

    Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany.

    Papers in Europe PMC
  6. 06
    van Geest FS11 papers · 2025

    Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.

    Papers in Europe PMC
  7. 07
    Guadaño-Ferraz A9 papers · 2025

    Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), Madrid, Spain.

    Papers in Europe PMC
  8. 08
    Peeters RP9 papers · 2026

    Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.

    Papers in Europe PMC
  9. 09
    Refetoff S9 papers · 2025

    Department of Medicine, The University of Chicago, Chicago, Illinois, USA.

    Papers in Europe PMC
  10. 10
    Kühnen P8 papers · 2025

    Department for Pediatric Endocrinology and Diabetology, Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany.

    Papers in Europe PMC

Clinical research

Is a treatment being tested?

4

interventional trials for this specific condition

4 interventional trials matched this specific condition name; none in our sample are currently recruiting.

Data as of 11 September 2026 · last trial check 28 July 2026

4 interventional trials — more than 77.2% of diseases in the trials denominator have none at all (5501 of 7126; this disease is at the 88.1th percentile).

low confidence · 88.1th percentile (trials denominator)

Recruiting interventional trials

From the matched ClinicalTrials.gov set

4 interventional trials matched after quoted-phrase search and title/condition post-filter.

No currently recruiting studies in the matched set. Open the same search on ClinicalTrials.gov.

Observational and natural-history studies

5 observational studies match this condition. These do not test a treatment and are not counted in the interventional-trial headline, but they are genuine research: natural-history work often defines the endpoints needed for a future rare-disease trial, and families may be able to enroll.

Recruiting or not-yet-recruiting

Open the complete matched search on ClinicalTrials.gov

Other registries (secondary)

Broader net from EU CTIS, ISRCTN, and ICTRP when available — deduped against ClinicalTrials.gov IDs already counted above. Dual-model LLM relevance gates what we keep. These rows are not added to the interventional headline.

raw 3 · after dedupe 3 · already on CT.gov 0 · kept 0 · parent 0 · uncertain 3 · dropped 0 · fetched 2026-07-29

Source notes: ictrp: Error: ICTRP public search unavailable (WHO portal is SPA-only; SOAP needs partnership). Tried: https://apps.who.int/tri

No secondary-registry studies passed dual-model relevance for this condition name (after dedupe).

Uncertain / not reviewed (3)

Where to find support

Condition-specific patient organisations, when Orphanet lists them, are on the disease’s Orphanet page. We also link umbrella groups that support undiagnosed and ultra-rare families.

Orphanet entry for Allan-Herndon-Dudley syndrome — check Associations / patient organisations on that page.

India — NPRD

Last verified 2026-07-26

This ORPHAcode is not on our curated NPRD list (direct or Mondo-parent match). That does not decide clinical eligibility; families in India should ask a notified Centre of Excellence about current coverage.

Hand-curated for this project. ORPHAcode mappings are best-effort and may be incomplete or imprecise for umbrella categories. Parent (Mondo) matches mean the policy lists a broader category — confirm eligibility with a Centre of Excellence. Financial entitlements summarised from public policy statements and may change. This is not official government guidance.

How we counted this

Europe PMC query (preferred label + any corrected label + Orphanet and Mondo exact synonyms, stoplisted; unioned with resolved MeSH labels when available). UMLS / OMIM / NCIT cross-references are stored on the overview but are not added to the query string.

("Allan-Herndon-Dudley syndrome" OR "MCT8 deficiency" OR "Monocarboxylate transporter 8 deficiency" OR "X-linked intellectual disability-hypotonia syndrome" OR "ALLAN-Herndon syndrome" OR "MCT8-Specific Thyroid Hormone Cell Transporter Deficiency" OR "MCT8-specific thyroid hormone cell Membrane transporter deficiency") OR ("SLC16A2" OR "SLC16A2 syndrome" OR "SLC16A2-related")

Run this search on Europe PMC

ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):

"Allan-Herndon-Dudley syndrome" OR "MCT8 deficiency" OR "Monocarboxylate transporter 8 deficiency" OR "X-linked intellectual disability-hypotonia syndrome" OR "ALLAN-Herndon syndrome" OR "MCT8-Specific Thyroid Hormone Cell Transporter Deficiency" OR "MCT8-specific thyroid hormone cell Membrane transporter deficiency"

Interventional trials matched via: phrase (mesh = registered under a MeSH descriptor no name phrase would catch; recall-expansion = gene / selected parent terms used only for trials).

Study-type breakdown: 4 interventional · 5 observational · 2 expanded access. Only interventional studies enter the trial headline.

Query health: ok — strategies attempted: phrase; with hits: phrase

Run this search on ClinicalTrials.gov

Synonyms dropped by stoplist: AHDS

Confidence reasoning

  • Preferred label is multi-word and distinctive
  • 1 synonym(s) dropped by stoplist (may under-count)
  • No label/synonym collisions with other diseases in this corpus
  • Publication count (1626) is extremely high with unknown/missing prevalence — treat as possible over-matching, not proven research intensity

Ingested 2026-07-26T12:16:26.166Z