Objective: To delineate the nature and origin of chromosomal aberration in a boy with mental retardation and multiple congenital deformities.
Methods: The karotypes of the proband and his parents were analyzed with routine G-banded chromosomal analysis. Genomic DNA was also analyzed with array comparative genomic hybridization (aCGH) assay.
Results: The karyotype of the proband was 46,XY,add(1)(p36.3). No karyotypic abnormality was detected in either parent. aCGH has identified a de novo 25.1 Mb duplication at 1q42q44 in the proband.
Conclusion: The de novo 1q42q44 duplication, which may be due to non-allelic homologous recombination mediated by low copy repeats, probably underlies the abnormalities in the proband.