Type of disease: Rare conditions
Hereditary geniospasm is a movement disorder that causes episodes of involuntary tremor of the chin and lower lip. The episodes may last anywhere from a few seconds to hours and may be brought on by stress or may occur without an apparent trigger. The episodes usually first appear in infancy or in early life 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) causing hereditary geniospasm have not been identified, a study of one family suggested that mutations in a gene on chromosome 9, located specifically at 9q13-q21, might cause the condition in some families. Results from other family studies suggest that there may be other genes that might be associated with hereditary geniospasm. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.