• A ring 4 chromosome was found in a boy with low birth weight, microcephaly, micrognathia, rounded broad nose, malformed ears, cleft soft palate, and retardation in growth and development. The ring 4 is formed by union of the ends after breakage and loss of the terminal parts of the short (p) arm and the long (q) arm. G-banded chromosome studies showed our patient to have a union at p16q35. Clinical findings in our patient were compared with those in others with the union at p16q35, p15q35, and p16q33. The patients with p15q35 had a deletion of more p-arm genetic material than those with the p16q35 union, and the patient with p16q33 had a greater loss of q-arm material. The loss of only a small part of the p16 band is associated with low birth weight, microcephaly, and retardation in growth and development.
(Am J Dis Child 1981;135:729-731)