Multiple congenital anomalies in a child with 47,XY,+der(8;9)(p10;p10): a case report: Complex small supernumerary marker chromosomes (sSMC) constitute one of the smallest subgroups of sSMC in general. Complex sSMC consist of chromosomal material derived from more than one chromosome. We report a complex sSMC derived from chromosomes 9 and 8, characterized as der(8;9)(p10;p10) resulting from unbalanced transition of maternal balanced translocation. Besides dysmorphic face and mental-motor retardation, the patient had Dandy-Walker malformation (DWM) in cranial MR also. As far as we are concerned, this is the first complex sSMC case comprising short arms of 8th and 9th chromosomes.