[Phenotypic and genetic analysis of a pedigree with 4p16 microduplication and 8p23 microdeletion]

To explore the nature and origin of chromosomal copy number variants (CNVs) in a pedigree affected with mental retardation.

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).

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.

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.