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Allan-Herndon-Dudley syndrome
ICD-10 Codes
Related ICD-10:
Description
Allan-Herndon-Dudley syndrome (AHDS) is a rare X-linked inherited disorder of brain development that causes both moderate to severe intellectual disability and problems with movement.
Characteristics of AHDS:
- Moderate to severe intellectual disability [1]
- Infantile hypotonia (low muscle tone) [3, 4, 5]
- Muscular hypoplasia (underdeveloped muscles) [4, 5]
- Spastic paraparesis (weakness and stiffness in the legs) [4, 5]
- Dystonic/athetoid movements (involuntary, disorganized muscle movements with short and repeated bursts of increased intensity) [2, 3]
Additional symptoms:
- Feeding difficulties in infancy [3, 9]
- Poor head control in infancy [9]
- Dysarthria (speech difficulties) [8]
- Global developmental delay [9]
It's worth noting that AHDS is a rare condition and the severity of its symptoms can vary from person to person.
Additional Characteristics
- Global developmental delay
- Moderate to severe intellectual disability
- Infantile hypotonia
- Muscular hypoplasia
- Spastic paraparesis
- athetoid movements
- Feeding difficulties in infancy
- Poor head control in infancy
- Dysarthria
Signs and Symptoms
Allan-Herndon-Dudley syndrome (AHDS) is a rare genetic disorder that affects brain development, leading to intellectual disability and neuromuscular problems. The signs and symptoms of AHDS can vary in severity and may include:
- Infantile hypotonia: Weakness or floppiness of the muscles in infancy
- Muscular hypoplasia: Underdevelopment of muscles, which can lead to muscle weakness and wasting
- Spastic paraparesis: Stiffness and weakness of the legs, leading to difficulty walking or moving
- Progressive hypertonicity: Increasing stiffness and rigidity of the limbs, with brisk reflexes and ankle clonus (involuntary contractions of the muscles)
- Poor head control: Difficulty maintaining balance and posture due to weak neck muscles
- Muscle weakness and wasting: Gradual weakening and shrinking of muscles, leading to difficulty moving or performing daily activities
- Joint deformities: Abnormal curvature or twisting of joints, particularly in the hands and feet
- Involuntary movements: Uncontrolled movements of the limbs, such as tremors or seizures
These symptoms can progress over time, with some individuals experiencing more severe impairments than others. Early diagnosis and intervention are crucial to managing the condition and improving quality of life.
References:
- [13] describes adults with AHDS as having "limber neck" or poor head control.
- [15] mentions progressively worsening muscle weakness, stiffness, exaggerated reflexes, joint deformities, and involuntary movements of the limbs eventually occurring in individuals with AHDS.
Additional Symptoms
- **Infantile hypotonia**
- **Muscular hypoplasia**
- **Spastic paraparesis**
- **Progressive hypertonicity**
- **Poor head control**
- **Muscle weakness and wasting**
- **Joint deformities**
- **Involuntary movements**
Diagnostic Tests
Allan-Herndon-Dudley syndrome, also known as MCT8 deficiency, is a rare genetic disorder that affects boys. The diagnostic tests for this condition are crucial in confirming the diagnosis.
Diagnostic Tests:
- Genetic Testing: Molecular genetic testing can confirm the presence of mutations in the SLC16A2 gene, which codes for the monoc
Additional Diagnostic Tests
- Genetic Testing
- Molecular genetic testing
- mutations in the SLC16A2 gene
Treatment
Current Status of Drug Treatment for Allan-Herndon-Dudley Syndrome
Allan-Herndon-Dudley syndrome (AHDS), also known as MCT8 deficiency, is a rare genetic disorder that affects a child's cognition, mobility, and overall health. As of now, there is no approved therapeutic treatment available for patients with AHDS.
Experimental Treatments
However, researchers are exploring various forms of thyroid hormone therapy to potentially alleviate the symptoms of AHDS. One such experimental treatment is Triac (3,3',5-tri-iodothyroacetic acid, or tiratricol), a T3-analogue that has shown promise in reducing the devastating neurological symptoms associated with AHDS.
- A recent study published in the peer-reviewed journal Thyroid identified a gene therapy that can potentially help prevent or reduce the neurological symptoms in patients diagnosed with AHDS [1].
- Another study, conducted by Cedars-Sinai and the University of Chicago, found that Triac may be beneficial in treating the symptoms of AHDS [2].
Current Management
At present, management of AHDS consists of supportive measures, including physical, occupational, and speech therapy. Dystonia, a common symptom of AHDS, can be treated with certain medications, such as anticholinergics, L-DOPA, carbamazepine, or lioresol [3].
Future Directions
While there is no approved treatment for AHDS at this time, ongoing research using different forms of thyroid hormone therapy holds promise for the development of effective treatments in the future.
References:
[1] Cedars-Sinai and University of Chicago study on gene therapy for AHDS (Thyroid journal)
[2] Triac in the treatment of Allan-Herndon-Dudley syndrome (Bauer AJ, 2019)
[3] Management of dystonia in AHDS patients (physical, occupational, and speech therapy)
Recommended Medications
- Gene Therapy
- Triac
- Thyroid Hormone Therapy
đź’Š Drug information is sourced from ChEBI (Chemical Entities of Biological Interest) database. Always consult with a healthcare professional before starting any medication. Click on any medication name for detailed information.
Differential Diagnosis
Allan-Herndon-Dudley syndrome (AHDS) is a rare X-linked inherited disorder that causes moderate to severe intellectual disability and problems with speech and movement [4]. When diagnosing AHDS, it's essential to consider differential diagnoses, which are conditions that share similar symptoms or characteristics.
According to medical literature, the main differential diagnoses for AHDS include:
- Pelizaeus-Merzbacher disease: a rare genetic disorder that affects the nervous system and causes intellectual disability, seizures, and muscle weakness [6].
- MECP2 duplication syndrome: a genetic disorder that affects the X chromosome and causes intellectual disability, delayed speech development, and problems with movement [6].
- X-linked intellectual disability conditions associated with ataxia, spastic paraplegia or muscle hypoplasia:
- X-linked intellectual disability-spastic paraplegia with iron deposits syndrome: a rare genetic disorder that affects the nervous system and causes intellectual disability, seizures, and muscle weakness [7].
- X-linked progressive cerebellar ataxia: a rare genetic disorder that affects the nervous system and causes problems with coordination and balance [7].
- Spastic paraplegia type 2: a rare genetic disorder that affects the nervous system and causes intellectual disability, seizures, and muscle weakness [7].
These differential diagnoses are essential to consider when diagnosing AHDS, as they share similar symptoms or characteristics. A comprehensive diagnostic evaluation, including genetic testing and clinical assessment, is necessary to accurately diagnose AHDS and rule out these differential diagnoses.
References:
[4] August 23, 2024 - Allan–Herndon–Dudley syndrome is a rare X-linked inherited disorder of brain development that causes both moderate to severe intellectual disability and problems with speech and movement. [6] MCT8 is the only gene known to be associated with Allan-Herndon-Dudley syndrome. Differential diagnoses include Pelizaeus-Merzbacher disease and MECP2 duplication syndrome, both of which are available for clinical testing in our lab. [7] 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.
Additional Differential Diagnoses
- X-linked intellectual disability-spastic paraplegia with iron deposits syndrome
- X-linked progressive cerebellar ataxia
- Spastic paraplegia type 2
- obsolete MECP2 duplication syndrome
- Pelizaeus-Merzbacher disease
- hypomyelinating leukodystrophy
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- hypomyelinating leukodystrophy 5
- hypomyelinating leukodystrophy 12
- hypomyelinating leukodystrophy 15
- hypomyelinating leukodystrophy 17
- hypomyelinating leukodystrophy 16
Additional Information
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