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Disease Profile

Madras motor neuron disease

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

Unknown

Age of onset

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ICD-10

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Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

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Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

MMND

Summary

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.
orphanet

Orpha Number: 137867

Definition
Madras motor neuron disease (MMND) is characterized by weakness and atrophy of limbs, multiple lower cranial nerve palsies and sensorineural hearing loss.

Epidemiology
Less than 200 cases have be reported to date, predominantly from Southern India. Isolated MMND cases have been reported from Thailand and Italy.

Clinical description
Onset occurs at a young age (often before the age of 15), with a slight male preponderance or equal sex distribution. Parental consanguinity has been reported in some cases. Main clinical features include thin habitus, wasting and weakness predominantly of the distal limb muscles, involvement of facial and bulbar muscles, and pyramidal dysfunction. Multiple cranial nerve palsies particularly involve the 7th, and the 9th to 12th cranial nerves. Hearing impairment was described in all patients. Optic atrophy is reported in some patients.

Etiology
The etiopathogenesis of MMND remains unknown. The majority of cases are sporadic. A few familial cases have been reported, but the mode of inheritance is yet to be determined. Inflammation and/or environmental factors may play a role in the etiology of MMND.

Diagnostic methods
Diagnosis is clinical and is supported by the association of benign focal atrophy of the extremities with hearing impairment. Neuroimaging studies may help to distinguish MMND from other motor neuron diseases.

Differential diagnosis
Differential diagnoses include amyotrophic lateral sclerosis, spinocerebellar ataxia syndromes, Brown-Vialetto-Van Laere syndrome, progressive muscular atrophy, post-polio progressive muscular atrophy, and spinal muscular atrophy (see these terms).

Management and treatment
Currently, there is no cure for MMND. Management should involve a multidisciplinary team (neurologists, physical therapists, occupational therapists, palliative care specialists, specialist nurses and psychologists) and should focus on the relief of symptoms. Symptomatic treatment and supportive care can help patients to maintain their daily living activities. Patients should be offered hearing aids.

Prognosis
The disease shows a slowly progressive but benign course. Most of the reported patients survived for over 30 years after the onset of the disease.

Visit the Orphanet disease page for more resources.

Symptoms

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.

Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Bulbar palsy
0001283
Sensorineural hearing impairment
0000407
30%-79% of people have these symptoms
Babinski sign
0003487
Distal amyotrophy
Distal muscle wasting
0003693
Distal muscle weakness
Weakness of outermost muscles
0002460
Hyperactive deep tendon reflexes
0006801
Limb fasciculations
0007289
Weak voice
Soft voice
0001621
5%-29% of people have these symptoms
Abnormal cerebellum morphology
Abnormality of the cerebellum
Cerebellar abnormalities
Cerebellar abnormality
Cerebellar anomaly

[ more ]

0001317
Dysphagia
Poor swallowing
Swallowing difficulties
Swallowing difficulty

[ more ]

0002015
Optic atrophy
0000648
Reduced tendon reflexes
0001315
Schizophrenia
0100753
Tinnitus
Ringing in ears
Ringing in the ears

[ more ]

0000360
1%-4% of people have these symptoms
Facial palsy
Bell's palsy
0010628
Reduced visual acuity
Decreased clarity of vision
0007663

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.

In-Depth Information

  • 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 Madras motor neuron disease. Click on the link to view a sample search on this topic.