HHHH stands for hereditary
hemihypotrophy, hemiparesis, and hemiathetosis. Characterized by congenital
unilateral (left or right) hemiparesis with subsequent development of
hemihypoplasia and athetoid posturing of the left hand. Other clinical
features include hemiatrophy, involuntary movements, and seizures. It has
been suggested that either an autosomal dominant or X-linked inheritance
is likely.