Hereditary defect of the sacrum.

A family in which both the mother and two of her daughters had partial agenesis of the sacrum and coccygeal bones is presented. Further studies demonstrate a neurogenic bladder and a presacral mass in the 4-year-old girl who had severe urinary incontinence. The mode of inheritance in this entity may be x-linked dominant as has been suggested. Previously by Cohn and Bay-Nielsen (1969). The gene may act as a lethal factors in hemizygous males. A brief review of the literature showed a remarkable paucity of reports on the hereditary aspects of sacrococcygeal defects in man. It is concluded that this may be misleading, since the true incidence of hereditary sacroccygeal deformities can not possibly be established until family members of the probands are also examined radiologically.