Type : Phenotype or locus, molecular basis unknown;
Alternative titles and symbols : Trembling chin;
Description : Geniospasm is characterized by spontaneous intermittent involuntary quivering or trembling
of the chin that is intensified by stress or anxiety. The movements are first noticed
in infancy or childhood and usually abate by late adulthood (Wadlington, 1958; Danek
et al., 1991).;