• chromosome 11p 19p marker;
  • congenital abnormalities;
  • intellectual disability;
  • mosaicism;
  • supernumerary marker chromosome


Unstable, gene-rich pericentric regions have been associated with various structural aberrations including small supernumerary marker chromosomes (sSMCs). We hereby report on a complex pure mosaic sSMCs derived from chromosomes 11 and 19 in a child featuring multiple congenital anomalies. As indicated by microarray analysis, the sSMCs have involved materials from 11p11.12 [RIGHTWARDS ARROW] q12.1 and 19p12 [RIGHTWARDS ARROW] q12 in complex forms (with four cell lines harboring from 1 to 4 sSMCs) in all peripheral blood lymphocytes. The patient featured facial dysmorphism, generalized hypotonia, cryptorchidism, transverse palmar creases, cerebral hemorrhage, atrial septal defect secundum, strabismus, epilepsy, immunodeficiency, and severe cognitive and motor impairment. Literature review indicated this to be a unique sSMCs case simultaneously involving chromosomes 11 and 19, with one sSMC containing materials from the both chromosomes. We propose that the involved chromosomal regions may contain dosage-sensitive genes which are important for the development, and that the sSMCs derived from multiple origins have formed by a complex mechanism. © 2011 Wiley Periodicals, Inc.