Structural aberrations of chromosome 18. II. The 18q- syndrome. Report of three cases.

3 cases of the 18q- syndrome, 2 boys and 1 girl, are presented, and a comparison with data from the literature is given. The following features are typical of the syndrome: short stature, mental retardation, muscular hypotonia, a peculiar dysmorphia of the face and ears, cryptorchidism and small scrotum in males, proximally implanted thumbs, tapering fingers, excess of whorls on the fingertips, and dorsally implanted second toes. Midface hypoplasia with hypertelorism and cleft palate, as well as strabismus, were present in 2 of our patients, whereas all 3 showed nystagmus and prominence of anthelix and antitragus. In addition, 2 patients exhibited narrow ear canals and impaired hearing. One patient had coloboma of the iris and choroid, pale optic discs, and cleft lip; another had umbilical and inguinal hernias. Two cases represented de novo deletions of the long arm of chromosomes 18, whereas the karyotype of the father of third case revealed a balanced translocation t(15;18)(q24;q21).