Molecular refinement of karyotype: Beyond the cytogenetic band

Purpose: Illustrate the use of molecular methodologies to delineate subtle, de novo, chromosome aberrations and determine the presence, or absence, of known genes, allowing improved predictions of long-term phenotypic effect. Method: High-resolution chromosome analysis followed by FISH and microsate llite analysis to determine the extent and parental origin of the abnormali ties. Results: Four de novo deletions involving chromosomes 5q, 10q, and 16 p were delineated molecularly. Specific genes were shown to be, or not to b e, involved in each aberration, refining karyotype-genotype correlation. Co nclusion: Molecular characterization of subtle chromosomal aberrations can provide information to assist in predicting clinical outcome in cases invol ving genes known to have an effect due to haploinsufficiency or aberrant ge ne dosage.