Mixed Motor Disorder: Essential Tremor Families With Heterogeneous Motor Phenomenology

Area of Science:

• Neurology
• Movement Disorders
• Genetics

Background:

• Essential tremor (ET) is a common movement disorder.
• Co-occurrence of ET with Parkinson disease (PD) and dystonia is observed.
• Familial aggregation suggests non-random co-occurrence of these disorders.

Purpose of the Study:

• To present four families with Essential Tremor (ET) exhibiting heterogeneous motor phenotypes.
• To discuss the implications of mixed motor disorders within families.
• To highlight the potential for combined diagnoses of ET, PD, and dystonia.

Main Methods:

• Enrolled ET cases and relatives in the Family Study of Essential Tremor.
• Conducted phenotyping through neurologic examinations by a movement disorders neurologist.

Main Results:

• Four families with 14 affected individuals were studied.
• Diagnoses included ET, PD, ET + PD, and ET + dystonia.
• In mixed cases, ET was the earliest and predominant phenotype.

Conclusions:

• These three disorders (ET, dystonia, PD) can co-occur within individuals and across family members.
• The concept of mixed motor disorders should be considered in clinical practice.
• Family history may reveal a mix of motor disorders, influencing diagnosis.