Origin of a Derivative Chromosome 20 Detected by SKY Analysis

We used a newly developed molecular cytogenetic technique, namely, spectral karyotyping (SKY) for all 24 chromosomes to study a baby with a derivative chromosome of unknown origin. The proband had severe psychomotor retardation, growth and mental retardation, epilepsy, craniofacial anomalies, prominent nasal bridge, and low-set dysplastic ears, clinodactyly, and malformations of heart, lungs, abdomen, and limbs. Cytogenetic analysis revealed a de novo add(20)(q13.3)in which a small additional material of unknown origin was attached to the terminal long arm of one chromosome 20. SKY analysis was thus performed to identify the origin and dual-color FISH analysis was used to further delineate the aberration. The SKY results showed that the additional material on the der(20)was chromosome 5 in origin and thus the child has partial monosomy for 20q13.3→qter and partial trisomy for 5q33→qter. This case illustrates the powerfulness of SKY to identify additional material in de novo situations where the segment is too small to test the origin by conventional G-banding and FISH analysis.

並列關鍵字

derivative chromosome 20 ； chromosome 5 ； spectral karyotyping ； SKY ； G-banding ； FISH

國際替代計量

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