ORPHA:59
Allan-Herndon-Dudley syndrome
Synonyms: AHDS · MCT8 deficiency · Monocarboxylate transporter 8 deficiency · X-linked intellectual disability-hypotonia syndrome
- Type
- Disease
- Group
- Disorder
- Inheritance
- X-linked recessive
- Age of onset
- Antenatal, Infancy, Neonatal
- Status
- active
A rare X-linked syndromic intellectual disability with neuromuscular involvement characterized by a varying degree of neurodevelopmental delay including hypotonia, hypokinesia, dystonia and spasticity, and a wide range of clinical sequelae secondary to chronic peripheral thyrotoxicosis.
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Names in Orphadata languages
12 of 12 languages| Lang | Name | Synonyms |
|---|---|---|
| en | Allan-Herndon-Dudley syndrome | AHDS · MCT8 deficiency · Monocarboxylate transporter 8 deficiency · X-linked intellectual disability-hypotonia syndrome |
| fr | Syndrome d'Allan-Herndon-Dudley | Déficit en MCT8 · Déficit en transporteur 8 de monocarboxylate · Syndrome de déficience intellectuelle liée à l'X-hypotonie |
| de | Allan-Herndon-Dudley-Syndrom | AHDS · MCT8-Mangel · Monocarboxylat-Transporter 8-Mangel · X-chromosomale Intelligenzminderung mit Hypotonie |
| es | Síndrome de Allan-Herndon-Dudley | Deficiencia de MCT8 · Deficiencia del transportador de monocarboxilato 8 · SAHD · Síndrome de discapacidad intelectual-hipotonía ligado al cromosoma X |
| it | Sindrome di Allan-Herndon-Dudley | AHDS · Deficit del trasportatore 8 dei monocarbossilati · Deficit di MCT8 · Sindrome disabilità intellettiva legata all'X-ipotonia |
| nl | Syndroom van Allan-Herndon-Dudley | AHDS · MCT8-deficiëntie · Monocarboxylaat-transporter 8-deficiëntie · X-gebonden intellectuele achterstand - hypotonie-syndroom |
| pt | Síndrome Allan-Herndon-Dudley | AHDS · Deficiência MCT8 · Deficiência do transportador de monocarboxilato 8 · Síndrome de perturbação do desenvolvimento intelectual ligado ao X-hipotonia |
| pl | Zespół Allana, Herndona i Dudley'a | AHDS · Niedobór MCT8 · Niedobór transportera jednowęglanów 8 · Niepełnosprawność intelektualna sprzężona z chromosomem X - hipotonia |
| cs | Allanův-Herndonův-Dudleyův syndrom | AHDS · Deficit MCT8 · Deficit monokarboxylátového transportéru 8 · Syndrom zahrnující X-vázané mentální postižení a hypotonii · Allan-Herndon-Dudleyův syndrom |
| uk | Синдром Аллана-Херндона-Дадлі | AHDS · Дефіцит MCT8 · Дефіцит монокарбоксилатного транспортера 8 · Х-зчеплений синдром інтелектуальної недостатності-гіпотонії |
| zh | Allan-Herndon-Dudley综合征 | X连锁智力障碍-肌张力低下综合征 |
| tr | Allan-Herndon-Dudley sendromu | AHDS · MCT8 eksikliği · Monokarboksilat taşıyıcı 8 eksikliği · X'e bağlı zihinsel yetersizlik-hipotoni sendromu |
Definition in:
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Cross-references
qualifier = Orphanet mapping relation| Source | Code | Qualifier | ICD relation | Validation |
|---|---|---|---|---|
| OMIM | 300523 | E | validated | |
| ICD-10 | E03.8 | NTBT | attributed | validated |
| ICD-11 | 5A00.0Y | NTBT | index | validated |
| MONDO | 0010354 | E | validated | |
| MeSH | C537047 | E | validated | |
| UMLS | C0795889 | E | validated | |
| GARD | 5617 | E | validated | |
| MedDRA | 10078821 | E | validated |
E exact · NTBT this ORPHAcode is narrower than the target · BTNT broader than the target · ND not decided.
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Classification
Preferential parent (Orphanet linearisation):
Parents in the classifications (3):
- ORPHA:320350Pure or complex X-linked spastic paraplegia
rare genetic diseases; rare neurological diseases - ORPHA:611314Rare syndromic intellectual disability without multiple congenital anomalies/dysmorphic syndrome
rare genetic diseases; rare neurological diseases - ORPHA:596426Syndrome of reduced sensitivity to thyroid hormone
rare genetic diseases; rare endocrine diseases
No children.
Codes that Orphanet moved or referred to this one:
- ORPHA:85337X-linked intellectual disability, Zorick type moved to · inactive
- ORPHA:163982X-linked intellectual disability-spastic quadriparesis syndrome moved to · inactive
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Genes
1 direct| Gene | Association | Status | HGNC | Ensembl | OMIM | Locus | Name | Source of validation |
|---|---|---|---|---|---|---|---|---|
| SLC16A2 | Disease-causing germline mutation(s) in | Assessed | HGNC:10923 | ENSG00000147100 | 300095 | Xq13.2 | solute carrier family 16 member 2 | 20301789[PMID]_18398436[PMID] |
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Prevalence and incidence
3 records| Type | Class | Value | Area | Qualification | Validation | Source |
|---|---|---|---|---|---|---|
| Cases/families | 320 cases | Worldwide | Case(s) | Validated | 25905294[PMID] | |
| Point prevalence | Unknown | — | Worldwide | Class only | Validated | ORPHANET_25905294[PMID] |
| Point prevalence | <1 / 1 000 000 | — | Europe | Class only | Validated | European Medecines Agency 2017[OTHER] |
Value is Orphadata's ValMoy: the mean estimate per 100 000 for prevalence and incidence, the number of cases or families for case reports.
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HPO phenotypes
54 annotations · validated 2025-06-23| HPO | Term (as annotated by Orphanet) | Diagnostic |
|---|---|---|
| Very frequent (99-80%) | ||
| HP:0008936 | Axial hypotonia | |
| HP:0001249 | Intellectual disability | |
| Frequent (79-30%) | ||
| HP:0007256 | Abnormal pyramidal sign | |
| HP:0002926 | Abnormality of thyroid physiology | |
| HP:0001251 | Ataxia | |
| HP:0012444 | Brain atrophy | |
| HP:0001266 | Choreoathetosis | |
| HP:0045082 | Decreased body mass index | |
| HP:0031936 | Delayed ability to walk | |
| HP:0012448 | Delayed myelination | |
| HP:0000750 | Delayed speech and language development | |
| HP:0001332 | Dystonia | |
| HP:0001531 | Failure to thrive in infancy | |
| HP:0008872 | Feeding difficulties in infancy | |
| HP:0000975 | Hyperhidrosis | |
| HP:0001347 | Hyperreflexia | |
| HP:0000822 | Hypertension | |
| HP:0002375 | Hypokinesia | |
| HP:0011788 | Increased circulating free T3 | |
| HP:0002751 | Kyphoscoliosis | |
| HP:0000276 | Long face | |
| HP:0002058 | Myopathic facies | |
| HP:0000275 | Narrow face | |
| HP:0000767 | Pectus excavatum | |
| HP:0001763 | Pes planus | |
| HP:0008081 | Pes valgus | |
| HP:0002205 | Recurrent respiratory infections | |
| HP:0003202 | Skeletal muscle atrophy | |
| HP:0002360 | Sleep abnormality | |
| HP:0001257 | Spasticity | |
| HP:0001649 | Tachycardia | |
| Occasional (29-5%) | ||
| HP:0002071 | Abnormality of extrapyramidal motor function | |
| HP:0011448 | Ankle clonus | |
| HP:0003487 | Babinski sign | |
| HP:0001348 | Brisk reflexes | |
| HP:0000028 | Cryptorchidism | |
| HP:0001558 | Decreased fetal movement | |
| HP:0001371 | Flexion contracture | |
| HP:0003324 | Generalized muscle weakness | |
| HP:0002342 | Intellectual disability, moderate | |
| HP:0002509 | Limb hypertonia | |
| HP:0000252 | Microcephaly | |
| HP:0001319 | Neonatal hypotonia | |
| HP:0000639 | Nystagmus | |
| HP:0002421 | Poor head control | |
| HP:0006579 | Prolonged neonatal jaundice | |
| HP:0001250 | Seizure | |
| HP:0004322 | Short stature | |
| HP:0002510 | Spastic tetraplegia | |
| Very rare (<4-1%) | ||
| HP:0100660 | Dyskinesia | |
| HP:0004488 | Macrocephaly at birth | |
| HP:0001561 | Polyhydramnios | |
| HP:0001622 | Premature birth | |
| HP:0001518 | Small for gestational age | |
Run the differential on the 2 obligate / very frequent terms
Annotation source: 20301789[PMID]
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Sources for this card
- Orphanet page: orpha.net/en/disease/detail/59
- This record as JSON: /data/d/59.json