Detailed analysis of 26 cases of 1q partial duplication/triplication syndrome.

Partial 1q trisomy syndrome is a rare disorder. Because unbalanced chromosomal translocations often occur with 1q trisomy, it is difficult to determine whether patient symptoms are related to 1q trisomy or other chromosomal abnormalities. The present study evaluated genotype-phenotype correlations of 26 cases diagnosed with 1q partial trisomy syndrome. DNA microarray was used to investigate the duplication/triplication region of 16 cases. Although there was no overlapping region common to all 26 cases, the 1q41-qter region was frequently involved. One case diagnosed as a pure interstitial trisomy of chromosome 1q by G-banded karyotype analysis was instead found to be a pure partial tetrasomy by CytoScan HD Array. In four 1q trisomy syndrome cases involving translocation, the translocated partner chromosome could not be detected by DNA microarray analyzes despite G-banded karyotype analysis, because there were a limited number of probes available for the partner region. DNA microarray and G-banded karyotyping techniques were therefore shown to be compensatory diagnostic tools that should be used by clinicians who suspect chromosomal abnormalities. It is important to continue recruiting affected patients and observe and monitor their symptoms to reveal genotype-phenotype correlations and to fully understand their prognosis and identify causal regions of symptoms.