Holly Manderfeld, age 14, of Utica, N.Y., for her question:

WHAT IS GIGANTISM?

Gigantism is excessive symmetrical growth, especially of the arms and legs, accompanied by a corresponding growth of the entire body. In humans, when gigantism begins in childhood before normal ossification has been completed, it is usually caused by overactivity of the anterior pituitary gland in production of the growth hormone.

Hereditary defects that prevent normal ossification at the time of puberty, and thus permit continued growth, may also cause a type of gigantism.

Because the growth hormone depresses the secretory powers of the gonads, gigantism may be accompanied by weakened sexual function and is then called eunuchoid gigantism. Gigantism may occur without disturbance in sex function, however.

Individuals affected by either type of gigantism are muscularly weak.

Acromegaly, a related condition caused by excessive production of the pituitary growth hormone, occurs in the third decade of life. It usually results in excessive growth of the hands, feet and chin.