A dysmorphia case of , developmental delay, growth retardation and having normal standard chromosomal karyotype was selected to study. An (aCGH) micro -array was performed and indicated that this patient has a hemizygous telomeric terminal deletion at the tip of the chromosome 12q starting from 12q24.31 and extending to the end of the q arm. Besides this large deletion one novel and seven previously reported copy number variations throughout the whole genome were identified.Confirmatory Real Time PCR and MLPA experiments were performed to validate the aCGH results in the region. These experiments established the presence of the deletion. To further validate and physically show the deletion a FISH assay was also performed on the interphase nuclei and metaphase spreads. These results indicated the presence of mosaicism in the labelled nuclei and spreads.