What are the other Names for this Condition? (Also known as/Synonyms)

• Familial Trembling of the Chin
• Geniospasm
• Hereditary Chin Tremor/Myoclonus

What is Hereditary Geniospasm? (Definition/Background Information)

• Hereditary Geniospasm is a movement disorder that causes episodes of involuntary tremors of the chin and lower lip
• The episodes may last anywhere from a few seconds to hours and may occur spontaneously or be brought on by stress
• The episodes usually first appear in infancy or childhood and tend to lessen in frequency with age
• Hereditary Geniospasm is believed to be inherited in an autosomal dominant pattern. Although the exact gene(s) that cause the condition are unknown, it has been suggested that mutations in a gene on chromosome 9 may be responsible in some families

(Source: Hereditary Geniospasm; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Hereditary Geniospasm? (Age and Sex Distribution)

• Hereditary Geniospasm is an extremely rare congenital disorder. Only about 25 families with the condition have been reported in the medical literature
• The presentation of symptoms may occur in infancy or childhood
• Both males and females may be affected. However, the disorder is slightly more frequent in males 
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Hereditary Geniospasm? (Predisposing Factors)

• A positive family history may be an important risk factor, since Hereditary Geniospasm is inherited
• Currently, no other risk factors have been clearly identified for this disorder

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Hereditary Geniospasm? (Etiology)

• The gene mutation that causes Hereditary Geniospasm is not known at the present time
• However, the causative gene has been localized to chromosome 9
• The disorder is inherited in an autosomal dominant manner

Autosomal dominant inheritance: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.

What are the Signs and Symptoms of Hereditary Geniospasm?

The signs and symptoms of Hereditary Geniospasm may be triggered by strong emotions or stress, and include:

• Involuntary trembling of chin and/or lower lips (which may occur during sleep as well)
• Abnormal sleep patterns

How is Hereditary Geniospasm Diagnosed?

Hereditary Geniospasm is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Hereditary Geniospasm?

The complications of Hereditary Geniospasm may include:

• Social embarrassment
• Anxiety

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Hereditary Geniospasm Treated?

There is no cure for Hereditary Geniospasm, since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complication that develops. The treatment methods may include:

• Medication(s) for muscle spasms (such as benzodiazepines)
• Anticonvulsant medications
• Botulinum toxin

How can Hereditary Geniospasm be Prevented?

Currently, Hereditary Geniospasm may not be preventable, since it is a genetic disorder.

• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Hereditary Geniospasm? (Outcomes/Resolutions)

• The prognosis of Hereditary Geniospasm is dependent upon the severity of the signs and symptoms and associated complications, if any
• The disorder is considered benign, and episodes of chin trembling may become less frequent with age
• The prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Hereditary Geniospasm:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/