This progressive neurodegenerative disorder is characterized by motor disturbances, cognitive loss, and psychiatric manifestations. Affected individuals develop a distinctive choreic movement disorder that has an insidious onset in the fourth to fifth decade of life and gradually worsens over a period of 10-20 years until death. A juvenile form of Huntington's disease exists, with a preponderance of paternal transmission of the disease. The term gonadal dysgenesis applies to persons who have streak gonads rather than ovaries. Affected individuals lack germ cells and show hypogonadism at puberty.
Affected individuals undergo breast development and feminization at puberty.
Despite pubertal feminization, some individuals with androgen insensitivity show clitoral enlargement and labioscrotal fusion. In complete androgen insensitivity, antim llerian hormone is synthesized as in the normal testis. Affected individuals undergo breast development, but areolae are often pale and underdeveloped. Such individuals are said to have incomplete androgen insensitivity. The number of common mendelian diseases in which the molecular genetics are sufficiently understood to allow this sort of diagnosis is now large and rapidly expanding.