DGM (Dutch-German Mennonite)

Inheritance: autosomal dominant
Genes: c1q42

Ataxia
Episodic ataxia with vertigo and tinnitus
EA3

Unsteadiness
Ataxia
Dizziness
Tinnitus
Vertigo
Ringing in ears
Myokymia
Muscle disease
CM
Blurred vision
Headache
Double vision
Weakness

Episodic Ataxia, Type 3

Clinical Characteristics

General description (for patients):

Patients with this condition suffer periodic attacks of dizziness, unsteadiness, twitching of facial muscles, and ringing in their ears.  The dizziness may be severe enough to cause severe balance problems and falling.  The most common age of onset is 13 years.  A widely used medication, Diamox, dramatically decreases symptoms.  Attacks may last for minutes, but occasional longer episodes lasting for hours, can lead to nausea, vomiting, and headaches.  Rare individuals have seizures.

Medical description: 

This seems to be a unique form of episodic ataxia in its excellent response to acetazolamide, the presence of vertigo and tinnitus, and somewhat later age of onset (median 13 years). Patients report generalized ataxia, vertigo, incoordination and imbalance sometimes leading to falls.  Episodes may occur daily (rarely), several times a week, or much less commonly.  Sometimes they last for minutes, sometimes for hours.  Longer-lasting attacks are often accompanied by nausea, vomiting and headaches.  Rare patients have had generalized seizures.  Interictal myokymia is common.

Genetics:

This autosomal dominant disorder has been linked to a region on chromosome 1 (1q42).  It has so far been reported only in Canadian Mennonites.

Treatment:

Acetazolamide (Diamox) is beneficial.

Prognosis:

Excellent prognosis if treated.  No permanent brain damage has been found.

Ancillary treatments and support:

Protection apparel for severe cases to protect from traumatic falls.

Specialists and specialty centers:

Neurologist.

References:

Cader, M.Z., Steckley, J.L., Dyment, D.A., McLauchlan, R.S., and Ebers, G.C.:  A genome-wide screen and linkage mapping for a large pedigree with episodic ataxia.  Neurology 65: 156-158, 2005.  PubMed ID: 16009908

Steckley, J.L., Ebers, G.C., Cader, M.Z., and McLachlan, R.S.:  An autosomal dominant disorder with episodic ataxia, vertigo, and tinnitus.  Neurology 57: 1499-1502, 2001.  PubMed ID: 11673600

Resources:

Genetics Home Reference