Identification of a rare de novo three-way complex t(5;20;8)(q31;p11.2;p21) with microdeletions on 5q31.2, 5q31.3, and 8p23.2 in a patient with hearing loss and global developmental delay: case report

Abstract

Background: Complex chromosome rearrangements (CCRs), which involve more than two breakpoints on two or more chromosomes, are uncommon occurrences. Although most CCRs appear balanced at the level of the light microscope, many demonstrate cryptic, submicroscopic imbalances at the translocation breakpoints.

Results: We report a female with hearing loss and global developmental delay with a complex three-way unbalanced translocation (5;20;8)(q31;p11.2;p21) resulting in microdeletions on 5q31.2, 5q31.3, and 8p23.2 identified by karyotyping, microarray analysis and fluorescence in situ hybridization.

Discussion: The microdeletion of bands 8p23.2 may be associated with the hearing impairment. Furthermore, the characterization of this patient's chromosomal abnormalities demonstrates the importance of integrated technologies within contemporary cytogenetics laboratories.

Figure 1

Proband at 5 months of age (A,B) and 6 days of age (C). Note myopathic face.

Figure 2

Summary of characterization of t(5;20;8)(q31;p11.2;p21). (A) Karyotype results for the patient; note the abnormal chromosome 20. (B) Microarray results showing complex rearrangement of 5q. The top plot shows a normal chromosome 5; the bottom plot shows the abnormal chromosome 5. Each clone represented on the array is arranged along the x-axis according to its location on the chromosome with the most distal/telomeric p-arm clones on the left and the most distal/telomeric q-arm clones on the right. The blue line plots represent the ratios from the first experiment for the case (control Cy5/patient Cy3) and the pink plots represent the ratios obtained from the second experiment for the case in which the dyes have been reversed (patient Cy5/control Cy3). (C) Microarray results showing deletion of 8p23.2. Microarray plots are arranged as in B from pter to qter. (D) FISH results for 5q31.2 (red), 5q tel (green) and 20 cen (green). (E) Locations on the derivative chromosome of 8p22 (red), 5q tel (green), and 20 cen (green).