Familial partial trisomy of the long arm of chromosome 10 (q24-26).

Two fourth cousins with a strikingly similar pattern of malformation and who have an unbalanced translocation (46, XY, -17, +t (17p; 10q) are described. From an analysis of the phenotypes of these patients and others reported with 10q trisomy, we propose that the trisomy 10q 24-26 syndrome includes: growth and mental retardation, a characteristic facies (microcephaly, flat face with spacious forehead, small nose, depressed nasal bridge, arched wide-spaced eyebrows, blepharophimosis, microphthalmia, low-set ears, bow-shaped mouth with prominent upper lip, micrognathia), palate anomalies (high-arched cleft or agenesis), congenital heart disease, and anomalies of the hands and feet. Anomalies common to the cousins, but not described in other patients with trisomy 10q, are believed to be expressions of a partial monosomy of 17p.