A Case with Mosaic Ring Chromosome 18

The classical mode of ring chromosome formation is by break forming in both arms of the affected chromosome, fusion of the breaking points and loss of the distal fragments. Ring chromosome of the chromosome 18 is relatively common among ring chromosomes and the rate of having typical clinical sings of 18p and 18q sydromes vary related to the length of the deletion in 18p and 18q. Ring 18 phenotype is characterised by growth retardation, mental retardation and nonspecific abnormalities, also facial dysmorphism and malformations may be observed. Our case referred with congenital malformation, motor mental retardation (MMR), short stature, high palate, pectus excavatus was evaluated genetically. GTL banding and FISH methods were performed for the metaphase plaques obtained from peripheral lymphocytes cultered for 72 hours. The karyotype of the case was detected to be 46,XX,r(18)[25]/46,XX[75] and confirmed by FISH analysis.