Array-CGH and clinical findings in a patient with a small supernumerary r(8) mosaicism: Small supernumerary ring chromosomes (sSRC) represent a subset of small supernumerary marker chromosomes (sSMC) where r(8) is relatively common. The phenotype sSRC(8) ranges from almost normal to variable degrees of abnormalities in mosaic or non-mosaic conditions. We present a new patient of de novo mosaic supernumerary ring chromosome 8 which has trisomy of a region of chromosome 8p11.21-q21.13. Mosaicism for a ring chromosome was showed by routine karyotyping that revealed a karyotype of mos47,XY,+r(?) /46,XY  and we performed array comparative genomic hybridization (array-CGH) in order to precisely define the extension about chromosomal origin of the duplicated region in a patient. Array-CGH analysis confirmed that the sSRC derived a 43.921 Mb genomic gain of chromosome 8 (p11.21-q21.13). Common clinical features of the patient included multiple congenital anomalies, developmental delay, thoracolumbar scoliosis, mild pulmonary stenosis, laryngomalacia, hypospadias and atypical facial appearance. With this study a patient involving mosaic trisomy 8p11.21-q21.13 along with clinical properties, is described and compared to previously reported cases involving partial trisomy 8q.