Absence of a lateral rectus muscle associated with duplication of the chromosome segment 7q32----q34.

Absence of the right lateral rectus muscle and hypoplasia of the left was found in a child with congenital esotropia. He had mental and physical retardation, bilateral optic nerve hypoplasia, and many minor dysmorphic features, including brachycephaly, high forehead, poorly folded, low set ears, epicanthic folds, exaggerated Cupid's bow, long philtrum, and single palmar creases. Unusual features were a markedly ridged palate and a plantar crease which passed from the first and second interspace across the lateral border of the foot. He was found to have an unbalanced karyotype with duplication of chromosome segment 7q32----q34 (46,XY,der(2),inv?ins(2;7) (q21;q32q34)mat). The mother, maternal aunt, and sister of the proband all had a balanced rearrangement and were phenotypically normal.