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Torsion dystonia is a rare genetic disease featuring painful, involuntary muscle contractions that trigger bodily distortions. There are different types of torsion dystonia, each affecting different parts of the body: cervical dystonia, which affects the spine, head, and neck; spasmodic dystonia, affecting the vocal cords; blepharospasm, affecting the eyelids; oromandibular dystonia, which affects the lips, tongue, and jaw; orofacial-buccal dystonia, otherwise known as Meige’s or Brueghal’s dystonia, which is a combination of oromandibular dystonia and blepharospasm; writer’s cramp, which affects the hand and the forearm; and early-onset torsion dystonia, a severe form of dystonia that begins in the arms or legs and progresses to the rest of the body.
Torsion dystonia, early-onset primary torsion dystonia in particular, primarily affects Jewish individuals of Ashkenazi (Eastern European) descent, although it affects non-Jewish individuals as well.
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Primary torsion dystonia amongst Ashkenazi Jewish individuals is caused by a TOR1A GAG deletion in the DYT1 gene. This mutation triggers the loss of the amino acid glutamic acid, which is part of the torsinA protein. The affected protein instigates the breakdown in communication between the neurons controlling muscle movement and control. While the disease is most often inherited, it can also occur spontaneously. The individual needs only one copy of the mutated gene to be affected, although 30 to 40 percent of individuals with the mutated gene do not exhibit any symptoms.
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Symptoms generally begin appearing around the age of 11 or 12, starting with contractions in one part of the body which progresses to other parts of the body over time. It takes approximately 5 years for the disease to progress to the point where the afflicted person is completely debilitated. Symptoms include: involuntary twisting when walking or using hands; tremors in the hands, feet, arms, and/or legs; jerking head movements; shifting, turning, or turning the head in any direction; pigeon toes; involuntary tongue popping and twisting; involuntary twisting of the mouth; and increased blinking. Afflicted individuals may also stutter and have difficulty speaking, have difficulty writing, and experience cramps in the legs and/or hands.
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While there is currently no cure for torsion dystonia, there are a number of ways its symptoms can be alleviated, depending on the needs of the patient. Nearly all patients will undergo some form of physical therapy, followed by a combination of medications such as Dopaminergic agents/Dopamine-depleting agents, Baclofen, Anticholinergics, Tetrabenezine, and Benzodiazepines. Some patients will undergo botulinum toxin injections, which blocks neurotransmitters. If the patient does not respond to medications or injections, surgery is an option.
This series describes the diseases tested for in the Ashkenazi Jewish Genetics Panel (AJGP).