Supernumerary Chromosome Marker Der(22)t(11;22) Resulting from a Maternal Balanced Translocation

Derivative 22 [der(22)] syndrome is a rare disorder associated with multiple congenitalanomalies including pre-auricular skin tags or pits, conotruncal heart defects, and profoundmental retardation. Der(22)t(11;22) is one of the causes of supernumerary chromosomemarkers (mar) in humans. We present a boy with developmental delay and multiple anomaliesconsistent with the supernumerary der(22) syndrome. Cytogenetic analysis showed anabnormal chromosome complement of 47, XY, +mar in all 50 cells analyzed. The karyotypeof his mother showed a reciprocal translocation over the distal bands 11q23 and 22q11,respectively, i.e., 46,XX,t(11;22)(q23.3;q11.2), and that of his father was 46,XY. Thus, thenature of the supernumerary chromosome markers was of der(22)t(11;22)(q23.3;q11.2). Theclinical features, including craniofacial dysmorphism, hypotonia, psychomotor retardation,heart defects, and urogenital anomalies, were the combined effects of partial trisomies forboth distal 11q and pericentromeric 22q.