Allan-Herndon-Dudley syndrome

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Other Names:

AHDS; Allan-Herndon syndrome; Monocarboxylate transporter-8 deficiency; AHDS; Allan-Herndon syndrome; Monocarboxylate transporter-8 deficiency; Triiodothyronine resistence; T3 resisitence; Intellectual disability and muscular atrophy; X-linked intellectual disability with hypotonia See More

Categories:

Congenital and Genetic Diseases; Endocrine Diseases; Nervous System Diseases

Summary Summary

Allan-Herndon-Dudley syndrome is a disorder of brain development that causes moderate to severe intellectual disability and problems with movement. This condition, which occurs exclusively in males, disrupts development from before birth. Although affected males have speech and a limited ability to communicate, they seem to enjoy interaction with others. Allan-Herndon-Dudley syndrome is caused by mutations in the SLC16A2 gene. It is inherited in an X-linked recessive manner.^[1]

Last updated: 6/12/2014

Symptoms Symptoms

Allan-Herndon-Dudley syndrome causes moderate to severe intellectual disability and problems with movement. People with this syndrome also have impaired speech and a limited ability to communicate. Most children have weak muscle tone (hypotonia) and underdevelopment of many muscles (muscle hypoplasia). As they get older, they often develop joint deformities called contractures, which restrict the movement of certain joints. Abnormal muscle stiffness (spasticity), muscle weakness, and involuntary movements of the arms and legs also limit mobility. As a result, many people with Allan-Herndon-Dudley syndrome are unable to walk independently and use a wheelchair in adulthood.^[1]

Last updated: 6/12/2014

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms	Other Names	Learn More: HPO ID
80%-99% of people have these symptoms
Abnormality of the neck		0000464
Absent speech	Absent speech development Lack of language development Lack of speech No speech development No speech or language development Nonverbal [ more ]	0001344
Aphasia	Difficulty finding words Losing words Loss of words [ more ]	0002381
Ataxia		0001251
Biparietal narrowing		0004422
Bowel incontinence	Loss of bowel control	0002607
Hyperreflexia	Increased reflexes	0001347
Hypoplasia of the musculature	Poorly developed skeletal musculature Underdeveloped muscle [ more ]	0009004
Hypoplasia of the zygomatic bone	Cheekbone underdevelopment Decreased size of cheekbone Underdevelopment of cheekbone [ more ]	0010669
Inability to walk		0002540
Intellectual disability, progressive	Mental retardation, progressive Progressive mental retardation [ more ]	0006887
Intellectual disability, severe	Early and severe mental retardation Mental retardation, severe Severe mental retardation [ more ]	0010864
Narrow face	Decreased breadth of face Decreased width of face [ more ]	0000275
Severe global developmental delay		0011344
Skeletal muscle atrophy	Muscle degeneration Muscle wasting [ more ]	0003202
Upslanted palpebral fissure	Upward slanting of the opening between the eyelids	0000582
Urinary incontinence	Loss of bladder control	0000020
30%-79% of people have these symptoms
Bilateral single transverse palmar creases		0007598
Joint stiffness	Stiff joint Stiff joints [ more ]	0001387
Macrotia	Large ears	0000400
Open mouth	Gaped jawed appearance Gaped mouthed appearance Slack jawed appearance [ more ]	0000194
5%-29% of people have these symptoms
Camptodactyly of finger	Permanent flexion of the finger	0100490
Cerebral calcification	Abnormal deposits of calcium in the brain	0002514
Proptosis	Bulging eye Eyeballs bulging out Prominent eyes Prominent globes Protruding eyes [ more ]	0000520
Protruding ear	Prominent ear Prominent ears [ more ]	0000411
Ptosis	Drooping upper eyelid	0000508
Rotary nystagmus		0001583
Scoliosis		0002650
Type I diabetes mellitus	Type 1 diabetes Type I diabetes [ more ]	0100651
Percent of people who have these symptoms is not available through HPO
Abnormal conjugate eye movement		0000549
Athetosis	Involuntary writhing movements in fingers, hands, toes, and feet	0002305
Babinski sign		0003487
Clonus		0002169
Congenital onset	Symptoms present at birth	0003577
Delayed CNS myelination		0002188
Drooling	Dribbling	0002307
Dysarthria	Difficulty articulating speech	0001260
Feeding difficulties in infancy		0008872
Flexion contracture	Flexed joint that cannot be straightened	0001371
Generalized amyotrophy	Diffuse skeletal muscle wasting Generalized muscle degeneration Muscle atrophy, generalized [ more ]	0003700
Hallux valgus	Bunion	0001822
Hypothyroidism	Underactive thyroid	0000821
Increased thyroid-stimulating hormone level		0002925
Irritability	Irritable	0000737
Leukodystrophy		0002415
Microcephaly	Abnormally small skull Decreased circumference of cranium Decreased size of skull Reduced head circumference Small head circumference [ more ]	0000252
Narrow forehead	Decreased width of the forehead	0000341
Neonatal hypotonia	Low muscle tone, in neonatal onset	0001319
Pectus excavatum	Funnel chest	0000767
Pes planus	Flat feet Flat foot [ more ]	0001763
Prominent antihelix		0000395
Spastic paraplegia		0001258
Spastic tetraplegia		0002510
Stahl ear		0100015
Underfolded superior helices		0008583
X-linked recessive inheritance		0001419

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Last updated: 2/1/2021

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Diagnosis Diagnosis

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

Find a Specialist Find a Specialist

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from MedlinePlus Genetics.

Related Diseases Related Diseases

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
Differential diagnoses include X-linked intellectual disability conditions associated with ataxia, spastic paraplegia or muscle hypoplasia such as X-linked intellectual disability-spastic paraplegia with iron deposits syndrome, X-linked progressive cerebellar ataxia, and spastic paraplegia type 2. Pelizaeus-Merzbacher disease and Snyder-Robinson syndrome should also be considered. Visit the Orphanet disease page for more information.

Conditions with similar signs and symptoms from Orphanet

Differential diagnoses include X-linked intellectual disability conditions associated with ataxia, spastic paraplegia or muscle hypoplasia such as X-linked intellectual disability-spastic paraplegia with iron deposits syndrome, X-linked progressive cerebellar ataxia, and spastic paraplegia type 2. Pelizaeus-Merzbacher disease and Snyder-Robinson syndrome should also be considered.

Visit the Orphanet disease page for more information.

Living With Living With

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Financial Resources

The Social Security Administration has included this condition in their Compassionate Allowances Initiative. This initiative speeds up the processing of disability claims for applicants with certain medical conditions that cause severe disability. More information about Compassionate Allowances and applying for Social Security disability is available online.

Learn More Learn More

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

Genetics Home Reference (GHR) contains information on Allan-Herndon-Dudley syndrome. This website is maintained by the National Library of Medicine.
The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

In-Depth Information

The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine.
Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
PubMed is a searchable database of medical literature and lists journal articles that discuss Allan-Herndon-Dudley syndrome. Click on the link to view a sample search on this topic.

News & Events News & Events

News

Rare Disease Day at NIH 2021
March 1, 2021

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Is cleft lip and/or palate frequently present in Allan-Herndon-Dudley syndrome? See answer

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References References

Allan-Herndon-Dudley syndrome. Genetics Home Reference (GHR). April 2013; http://ghr.nlm.nih.gov/condition/allan-herndon-dudley-syndrome. Accessed 6/12/2014.

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