C AUTOSOMAL TRISOMY WITH MOSAICISM: A NEW SYNDROME?

Abstract

The presence of a C trisomy with euploid mosaicism was observed in the blood and marrow cells of a 2-month-old boy. The autosomal nature of the supernumerary chromosome was inferred from the absence of sex chromatin bodies, the lack of "drumstick" appendages on polymorphs, and a failure to identify a late-replicating member among the submedian chromosomes of aneuploid cells which were studied by autoradiography. Malformations included an asymmetrical head, corneal opacity, abnormal ears, tapered fingers with joint limitations, anomalies of the right kidney, and a probable congenital heart defect. Analysis of amino acid excretion revealed a high renal clearance for proline, hydroxyproline, and glycine. The patient's condition has been compared to seven other patients with a C trisomy, five of which had euploid mosaicism. Certain recurrent findings, such as normal stature, advanced bone age, skeletal anomalies, particularly of the ribs and vertebrae, narrow pelvis, joint limitations, finger retractions, and hypertonicity, were noted. Therefore, it is possible that a rare trisomy for a C autosome exists which may be responsible for a definite syndrome.