RESUMO
OBJECTIVE@#To explore the nature and origin of chromosomal copy number variants (CNVs) in a pedigree affected with mental retardation.@*METHODS@#Genomic CNVs of the proband were analyzed by next generation sequencing (NGS). Chromosomal karyotypes of the proband and his relatives were analyzed with high-resolution karyotyping and fluorescence in situ hybridization (FISH).@*RESULTS@#Clinical phenotypes of the proband and other patients from the pedigree included mental retardation and mild dysmorphism. The results of NGS revealed that the proband carried a 16.24 Mb microduplication at 4p16.3-15.32 and a 2.2 Mb microdeletion at 8p23.3-23.2. Other patients of the pedigree harbored the same variants, while those without the phenotypes did not harbor the variants. The results of high-resolution karyotyping and FISH revealed that the mother of the proband carried a reciprocal translocation between 4p and 8p, and her karyotype was 46,XX,t(4;8)(p16;p23). No karyotypic abnormality was detected in his father.@*CONCLUSION@#The abnormal phenotypes of this pedigree may be attributed to 4p microduplication in conjunct with 8p microdeletion derived from a maternal balanced translocation between 4p and 8p.