Screening for subtelomeric chromosome abnormalities in children with idiopathic mental retardation using multiprobe telomeric FISH and the new MAPH telomeric assay.

Subtelomeric chromosomal abnormalities are emerging as an important cause of human genetic disorders. The scope of this investigation was to screen a selected group of children with idiopathic mental retardation for subtelomeric anomalies using the multiprobe telomeric FISH method and also to develop and test a new assay, the MAPH telomeric assay, in the same group of patients. The new MAPH telomeric assay uses the recently published MAPH methodology that permits the measurement of locus copy number by hybridisation with a specifically designed set of probes located at the end of human chromosomes.