The clinical syndrome of OGD in the female is displayed as hypogonadism and most commonly type I hyposmia ("anosmia"). The main pathologic findings are absence of the olfactory bulbs and tracts, hypoplasia of the hypothalamus, a normal pituitary gland, and normal appearing, although unstimulated, ovaries. The syndrome of OGD may be considered as an attenuated form of holoprosencephaly. Various facial abnormalities have been observed in patients with OGD and their families. Thorough neurologic examination may reveal other abnormalities. In the majority of cases the etiology of OGD is not known; however, among about one-fourth of the females, other members of the family exhibit either OGD or anosmia, implying a genetic basis. In this familial form of OGD some pedigrees suggest an X-chromosomal pattern and others, an autosomal inheritance pattern. Although hypogonadotropic hypogonadism is usually considered the only endocrinologic abnormality, stimulatory test of pituitary and hypothalamic function may reveal poor responses of growth hormone. ACTH, prolactin, and possibly MSH. The administration of LRH has shown varying pituitary gonadotropin responses, implying, in some instances, an associated pituitary malfunction. However, these observations may be the result of variations in technic and, therefore, further data are necessary to clarify this issue. Cyclic estrogen and progestin administration stimulates secondary sexual sex characteristics. Exogenous gonadotropins are capable of stimulating ovarian steroidogenesis and, in most patients, inducing ovulation. Thre pregnancies have been reported.