DYT-GNAL

Summary

• DYT-GNAL is a mostly adult-onset isolated dystonia (in which no additional neurologic abnormalities other than tremor are evident on neurologic examination). <ref>Deutschländer AB, Wszolek ZK. DYT-GNAL. 2019 Jan 3. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK535640/</ref>[1].
• The dystonia is most commonly focal and segmental, and rarely generalized.
• Dystonia is typically cervical in onset and commonly progresses to the cranial region (oromandibular/jaw, larynx, eyelids) and/or to one arm.
• DYT-GNAL tremor may be dystonic (i.e., occurring in a body part that shows at least minimal signs of dystonia) and may precede or follow the onset of dystonia).

Cause

DYT-GNAL caused by a heterozygous GNAL pathogenic variant has been reported in more than 60 individuals to date.

Inheritance

File:Autosomal dominant - en.svg

Autosomal dominant pattern, a 50/50 chance.

DYT-GNAL is typically inherited in an autosomal dominant manner (to date, 1 family with autosomal recessive inheritance of DYT-GNAL has been reported).

Signs and symptoms

DYT-GNAL is characterized by the following:

• Isolated; no neurologic abnormalities other than tremor evident on neurologic examination
• Age at onset typically in adulthood; rarely in childhood.
• Most commonly focal and segmental; rarely generalized ; and rarely laryngeal dystonia only.
• Onset typically in the cervical region and commonly progressing to the cranial region (oromandibular/jaw, larynx, blepharospasm) and/or to one arm

Diagnosis

DYT-GNAL should be considered in individuals with the following clinical findings, neuroimaging findings, and family history.<ref>Deutschländer AB, Wszolek ZK. DYT-GNAL. 2019 Jan 3. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK535640/</ref>[2]. Neuroimaging Studies

• Brain magnetic resonance imaging and computed tomography results are normal, showing no structural intracranial lesions that could be considered a cause of acquired dystonia.

The diagnosis of DYT-GNAL is established in a proband with isolated dystonia and a heterozygous GNAL pathogenic variant identified by molecular genetic testing.

Treatment

• While oral medication is usually the initial treatment of dystonia, experience in DYT-GNAL specifically is limited.
• Botulinum toxin intramuscular injections have improved cervical dystonia and dystonia affecting other sites in some patients with DYT-GNAL – as well as dystonia in selected muscles in patients with generalized dystonia.
• Deep-brain stimulation of the globus pallidus internus has been effective in a few patients with DYT-GNAL.
• Physical therapy may help prevent joint contractures and spine deformities.
• Treatment of depression and anxiety, commonly associated with cervical dystonia, is per standard practice.<ref>Deutschländer AB, Wszolek ZK. DYT-GNAL. 2019 Jan 3. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK535640/</ref>[3].

References

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NIH genetic and rare disease info

• NIH info on DYT-GNAL

DYT-GNAL is a rare disease.

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