Primed in situ labeling technique for subtelomeric rearrangements in 70 children with idiopathic mental retardation.

Subtelomeric rearrangements contribute to idiopathic mental retardation (MR), but most children with idiopathic MR do not show any chromosome abnormalities with standard cytogenetic analysis. The primed in situ labeling (PRINS) technique, using an oligonucleotide primer complementary to the telemetric repeat sequences (TTAGGG), can identify chromosome telomeric abnormality (deletion) in idiopathic MR children. In this study, seventy children with idiopathic MR were enrolled and subjected to PRINS. The results showed normal karyotype in all the children, subtelomeric rearrangements (1q del and 4q del) in 2 cases, which was confirmed by fluorescence in situ hybridization (FISH). It was concluded that PRINS is effective for the detection of subtelomeric rearrangements and may become a routine technique for cytogenetical abnormality screening.