Allan-Herndon-Dudley syndrome

Title

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. They also have impaired speech and a limited ability to communicate. Most children with this condition 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 become wheelchair-bound by adulthood.^[1]

Last updated: 6/12/2014

The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.

Signs and Symptoms	Approximate number of patients (when available)
Abnormality of the neck	Very frequent (present in 80%-99% of cases)
Absent speech	Very frequent (present in 80%-99% of cases)
Aphasia	Very frequent (present in 80%-99% of cases)
Ataxia	Very frequent (present in 80%-99% of cases)
Biparietal narrowing	Very frequent (present in 80%-99% of cases)
Bowel incontinence	Very frequent (present in 80%-99% of cases)
Hyperreflexia	Very frequent (present in 80%-99% of cases)
Hypoplasia of the musculature	Very frequent (present in 80%-99% of cases)
Hypoplasia of the zygomatic bone	Very frequent (present in 80%-99% of cases)
Inability to walk	Very frequent (present in 80%-99% of cases)
Intellectual disability, progressive	Very frequent (present in 80%-99% of cases)
Intellectual disability, severe	Very frequent (present in 80%-99% of cases)
Narrow face	Very frequent (present in 80%-99% of cases)
Severe global developmental delay	Very frequent (present in 80%-99% of cases)
Skeletal muscle atrophy	Very frequent (present in 80%-99% of cases)
Upslanted palpebral fissure	Very frequent (present in 80%-99% of cases)
Urinary incontinence	Very frequent (present in 80%-99% of cases)
Bilateral single transverse palmar creases	Frequent (present in 30%-79% of cases)
Joint stiffness	Frequent (present in 30%-79% of cases)
Macrotia	Frequent (present in 30%-79% of cases)
Open mouth	Frequent (present in 30%-79% of cases)
Camptodactyly of finger	Occasional (present in 5%-29% of cases)
Cerebral calcification	Occasional (present in 5%-29% of cases)
Proptosis	Occasional (present in 5%-29% of cases)
Protruding ear	Occasional (present in 5%-29% of cases)
Ptosis	Occasional (present in 5%-29% of cases)
Rotary nystagmus	Occasional (present in 5%-29% of cases)
Scoliosis	Occasional (present in 5%-29% of cases)
Type I diabetes mellitus	Occasional (present in 5%-29% of cases)
Abnormal conjugate eye movement	-
Athetosis	-
Babinski sign	-
Clonus	-
Congenital onset	-
Delayed CNS myelination	-
Drooling	-
Dysarthria	-
Feeding difficulties in infancy	-
Flexion contracture	-
Generalized amyotrophy	-
Hallux valgus	-
Hypothyroidism	-
Increased thyroid-stimulating hormone level	-
Irritability	-
Leukodystrophy	-
Microcephaly	-
Narrow forehead	-
Neonatal hypotonia	-
Pectus excavatum	-
Pes planus	-
Prominent antihelix	-
Spastic paraplegia	-
Spastic tetraplegia	-
Stahl ear	-
Underfolded superior helices	-
X-linked dominant inheritance	-

Last updated: 9/1/2017

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.

Do you have updated information on this condition? Let us know.

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.

Genetics 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 GeneTests, 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 Genetics Home Reference.

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

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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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