Clinical Utility of Testing

Because developmental delay is a frequent finding in chromosomal imbalance, the main focus for these assays has been in studies of individuals with idiopathic mental retardation (IMR). An average of 6% of individuals with IMR have an imbalance that involves one or more distal chromosomal segments.32 Based on these data, subtelomeric testing is the next logical step following a normal routine or (ideally) high-resolution karyotyping study, for individuals whose phenotype suggests an underlying chromosomal etiology. Subtelomeric panel testing is not routinely used for prenatal diagnosis at this time due to constraints of the test methodologies and to potential limitations in test interpretation in the absence of a well-defined pheno-type (see Interpretation of Test Results section below).

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